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201. What is a comproportionation reaction?
ⓐ. A reaction where two different elements are involved in the exchange of electrons
ⓑ. A reaction in which two compounds react to form a single product
ⓒ. A reaction where a single substance is both oxidized and reduced
ⓓ. A reaction that only occurs in the presence of light
Correct Answer: A reaction where a single substance is both oxidized and reduced
Explanation: A comproportionation reaction is a type of redox reaction where a single substance is simultaneously oxidized and reduced, leading to the formation of two different products with different oxidation states of the same element.
202. Which of the following is an example of a comproportionation reaction?
ⓐ. $2Na + Cl_2 \rightarrow 2NaCl$
ⓑ. $2H_2O_2 \rightarrow 2H_2O + O_2$
ⓒ. $3SO_2 + 2H_2O_2 \rightarrow 2H_2SO_3 + SO_2$
ⓓ. $C + O_2 \rightarrow CO_2$
Correct Answer: $2H_2O_2 \rightarrow 2H_2O + O_2$
Explanation: This reaction is an example of a comproportionation reaction where hydrogen peroxide ($H_2O_2$) decomposes. Some molecules of hydrogen peroxide are reduced to water ($H_2O$), and others are oxidized to oxygen gas ($O_2$), showing both oxidation and reduction of the same element (oxygen).
203. In the reaction $2H_2O_2 \rightarrow 2H_2O + O_2$, what happens to the oxygen in hydrogen peroxide?
ⓐ. Oxygen is reduced to form $H_2O$
ⓑ. Oxygen is oxidized to form $O_2$
ⓒ. Oxygen remains unchanged
ⓓ. Both oxidation and reduction occur for oxygen
Correct Answer: Both oxidation and reduction occur for oxygen
Explanation: In this reaction, oxygen undergoes both oxidation and reduction. Some oxygen atoms are reduced to form water ($H_2O$), while others are oxidized to form oxygen gas ($O_2$). This is a classic example of a comproportionation reaction.
204. Which of the following reactions is an example of a comproportionation reaction involving chlorine?
ⓐ. $Cl_2 + 2NaBr \rightarrow 2NaCl + Br_2$
ⓑ. $Cl_2 + H_2O \rightarrow HCl + HOCl$
ⓒ. $NaCl + AgNO_3 \rightarrow NaNO_3 + AgCl$
ⓓ. $Na + Cl_2 \rightarrow NaCl$
Correct Answer: $Cl_2 + H_2O \rightarrow HCl + HOCl$
Explanation: In this reaction, chlorine ($Cl_2$) undergoes comproportionation. One chlorine atom is reduced to chloride ($Cl^-$) in hydrochloric acid ($HCl$), while the other is oxidized to hypochlorite ($HOCl$). This is a classic example of a comproportionation reaction.
205. Which of the following is true about comproportionation reactions?
ⓐ. They always involve metals
ⓑ. They always involve non-metals
ⓒ. A single element is both oxidized and reduced
ⓓ. They always form only one product
Correct Answer: A single element is both oxidized and reduced
Explanation: In a comproportionation reaction, a single element undergoes both oxidation (loses electrons) and reduction (gains electrons). This results in two products with different oxidation states of the same element.
206. In the reaction $Cu^+ + Cu^{2+} \rightarrow 2Cu$, what happens to copper?
ⓐ. Copper is reduced
ⓑ. Copper is oxidized
ⓒ. Copper undergoes no change
ⓓ. Copper is both oxidized and reduced
Correct Answer: Copper is both oxidized and reduced
Explanation: In this reaction, copper in the +1 oxidation state ($Cu^+$) is oxidized to copper in the +2 oxidation state ($Cu^{2+}$), while copper in the +2 oxidation state ($Cu^{2+}$) is reduced to copper metal ($Cu$). This is an example of a comproportionation reaction.
207. Which of the following reactions is an example of a comproportionation reaction involving sulfur?
ⓐ. $SO_2 + H_2O \rightarrow H_2SO_3$
ⓑ. $2SO_2 + O_2 \rightarrow 2SO_3$
ⓒ. $2H_2S + O_2 \rightarrow 2H_2O + 2S$
ⓓ. $SO_2 + 2H_2O \rightarrow H_2SO_4$
Correct Answer: $2H_2S + O_2 \rightarrow 2H_2O + 2S$
Explanation: In this reaction, sulfur in hydrogen sulfide ($H_2S$) undergoes both oxidation and reduction. The sulfur atoms in $H_2S$ are oxidized to elemental sulfur ($S$), while others are reduced. This is a comproportionation reaction.
208. In the reaction $2Cu^+ + 2e^- \rightarrow Cu + Cu^{2+}$, which element undergoes both oxidation and reduction?
ⓐ. Copper
ⓑ. Hydrogen
ⓒ. Oxygen
ⓓ. Chlorine
Correct Answer: Copper
Explanation: In this reaction, copper ($Cu^+$) is oxidized to $Cu^{2+}$, while copper ($Cu^{+}$) is also reduced to elemental copper ($Cu$). This is a comproportionation reaction where copper undergoes both oxidation and reduction.
209. What is formed in the reaction $Cl_2 + H_2O \rightarrow HCl + HOCl$?
ⓐ. Hydrogen chloride and oxygen
ⓑ. Chlorine gas and water
ⓒ. Hydrochloric acid and hypochlorous acid
ⓓ. Sodium chloride and chlorine gas
Correct Answer: Hydrochloric acid and hypochlorous acid
Explanation: In this comproportionation reaction, chlorine ($Cl_2$) is both reduced to form hydrochloric acid ($HCl$) and oxidized to form hypochlorous acid ($HOCl$). This is a classic example of a non-metal undergoing disproportionation.
210. Which of the following statements is true about the reaction $Cl_2 + 2NaOH \rightarrow NaCl + NaOCl + H_2O$?
ⓐ. Chlorine is reduced and oxidized in the same reaction
ⓑ. Chlorine is only reduced
ⓒ. Chlorine is only oxidized
ⓓ. Sodium undergoes reduction
Correct Answer: Chlorine is reduced and oxidized in the same reaction
Explanation: In this reaction, chlorine ($Cl_2$) is reduced to chloride ($Cl^-$) and oxidized to hypochlorite ($OCl^-$) in the presence of sodium hydroxide ($NaOH$). This is a typical example of a comproportionation reaction.
211. Which of the following elements can undergo a comproportionation reaction?
ⓐ. Oxygen
ⓑ. Chlorine
ⓒ. Sodium
ⓓ. Magnesium
Correct Answer: Chlorine
Explanation: Chlorine is a common element that undergoes comproportionation reactions, as it can simultaneously undergo oxidation and reduction. An example is the reaction $Cl_2 + 2NaOH \rightarrow NaCl + NaOCl + H_2O$, where chlorine is both reduced and oxidized.
212. In the reaction $2H_2O_2 \rightarrow 2H_2O + O_2$, what happens to oxygen in hydrogen peroxide?
ⓐ. Oxygen is oxidized
ⓑ. Oxygen is reduced
ⓒ. Oxygen is unchanged
ⓓ. Both oxidation and reduction occur
Correct Answer: Both oxidation and reduction occur
Explanation: In this reaction, oxygen undergoes both oxidation and reduction. Some oxygen atoms are reduced to form water ($H_2O$), while others are oxidized to form oxygen gas ($O_2$). This is a comproportionation reaction, where a single substance undergoes both oxidation and reduction.
213. What is the key feature of a comproportionation reaction?
ⓐ. A single element is both oxidized and reduced
ⓑ. A substance gains electrons
ⓒ. A substance loses electrons
ⓓ. Only metals are involved
Correct Answer: A single element is both oxidized and reduced
Explanation: The key feature of a comproportionation reaction is that a single element undergoes both oxidation (losing electrons) and reduction (gaining electrons), forming products with different oxidation states of that element.
214. What is the first step in balancing a redox reaction using the oxidation number method?
ⓐ. Identify the oxidizing and reducing agents
ⓑ. Assign oxidation numbers to all elements in the reaction
ⓒ. Balance the number of atoms on both sides
ⓓ. Add electrons to balance the charge
Correct Answer: Assign oxidation numbers to all elements in the reaction
Explanation: The first step in the oxidation number method is to assign oxidation numbers to all elements in the reaction. This helps to determine which elements are oxidized and which are reduced, allowing you to identify the changes in oxidation numbers.
215. After assigning oxidation numbers, what is the next step in the oxidation number method for balancing redox reactions?
ⓐ. Identify the changes in oxidation numbers
ⓑ. Balance the number of atoms on both sides of the equation
ⓒ. Balance the charge by adding electrons
ⓓ. Multiply coefficients to adjust the oxygen atoms
Correct Answer: Identify the changes in oxidation numbers
Explanation: After assigning oxidation numbers, the next step is to identify the changes in oxidation numbers for the elements involved. This helps in determining how many electrons are gained or lost in the reaction, which is necessary for balancing the equation.
216. In the reaction $MnO_4^- + 8H^+ + 5e^- \rightarrow Mn^{2+} + 4H_2O$, how do the oxidation numbers of manganese change?
ⓐ. Manganese is oxidized from +2 to +7
ⓑ. Manganese is oxidized from +3 to +6
ⓒ. Manganese is reduced from +4 to +3
ⓓ. Manganese is reduced from +7 to +2
Correct Answer: Manganese is reduced from +7 to +2
Explanation: In this reaction, manganese in the permanganate ion ($MnO_4^-$) has an oxidation number of +7. In the product, manganese in the $Mn^{2+}$ ion has an oxidation number of +2. Therefore, manganese is reduced from +7 to +2.
217. After identifying the changes in oxidation numbers, what is the next step in balancing a redox reaction using the oxidation number method?
ⓐ. Add water molecules to balance oxygen
ⓑ. Add electrons to balance the changes in oxidation numbers
ⓒ. Add protons to balance hydrogen atoms
ⓓ. Adjust the coefficients of the reactants and products
Correct Answer: Add electrons to balance the changes in oxidation numbers
Explanation: After identifying the changes in oxidation numbers, the next step is to add electrons to balance the changes. Electrons are added to either the reduction half-reaction or the oxidation half-reaction to ensure that the total number of electrons lost equals the total number of electrons gained.
218. In the reaction $Cu^{2+} + 2e^- \rightarrow Cu$, how is the oxidation state of copper (Cu) changing?
ⓐ. Copper is reduced from +2 to 0
ⓑ. Copper is reduced from +1 to +2
ⓒ. Copper is oxidized from 0 to +2
ⓓ. Copper is oxidized from +2 to +3
Correct Answer: Copper is reduced from +2 to 0
Explanation: In this reaction, copper ions ($Cu^{2+}$) gain two electrons to form copper metal ($Cu$). The oxidation state of copper changes from +2 to 0, indicating reduction.
219. What is the next step after adding electrons to balance the oxidation numbers in a redox reaction?
ⓐ. Balance the number of atoms of each element
ⓑ. Adjust the coefficients of the products
ⓒ. Add water molecules to balance oxygen
ⓓ. Multiply the half-reactions to match the number of electrons
Correct Answer: Multiply the half-reactions to match the number of electrons
Explanation: After adding electrons to balance the oxidation numbers, the next step is to multiply the half-reactions by appropriate coefficients so that the number of electrons lost in the oxidation half-reaction equals the number of electrons gained in the reduction half-reaction.
220. In the reaction $2H_2O + 2e^- \rightarrow H_2 + 2OH^-$, what is the oxidation number of oxygen before and after the reaction?
ⓐ. 0 before, -2 after
ⓑ. -2 before, -2 after
ⓒ. -2 before, 0 after
ⓓ. -1 before, -2 after
Correct Answer: -2 before, -2 after
Explanation: In this reaction, oxygen in water ($H_2O$) has an oxidation number of -2. After the reaction, oxygen in hydroxide ions ($OH^-$) also has an oxidation number of -2. Therefore, the oxidation number of oxygen remains unchanged.
221. In the reaction $MnO_4^- + 8H^+ + 5e^- \rightarrow Mn^{2+} + 4H_2O$, how do you balance the electrons in the half-reaction?
ⓐ. Add 5 electrons to the left side of the equation
ⓑ. Add 5 electrons to the right side of the equation
ⓒ. Add 8 electrons to the right side of the equation
ⓓ. Add electrons to balance hydrogen
Correct Answer: Add 5 electrons to the left side of the equation
Explanation: In this half-reaction, manganese in $MnO_4^-$ is reduced from +7 to +2. To balance the change in oxidation states, 5 electrons are added to the left side of the equation, where they will be gained by manganese during the reduction process.
222. What is the final step in balancing a redox reaction using the oxidation number method?
ⓐ. Balance the charges by adding electrons
ⓑ. Add water to balance oxygen atoms
ⓒ. Adjust the coefficients of the reactants and products
ⓓ. Ensure the number of electrons gained equals the number of electrons lost
Correct Answer: Adjust the coefficients of the reactants and products
Explanation: After ensuring that the number of electrons gained equals the number of electrons lost, the final step is to adjust the coefficients of the reactants and products to balance the equation in terms of both mass and charge.
223. In the reaction $Cr_2O_7^{2-} + 14H^+ + 6e^- \rightarrow 2Cr^{3+} + 7H_2O$, how do you balance the equation using the oxidation number method?
ⓐ. Add 6 electrons to the right side
ⓑ. Balance the number of hydrogen atoms by adding $H_2O$
ⓒ. Multiply the half-reactions by 6
ⓓ. Add 6 electrons to the left side to balance the reduction half-reaction
Correct Answer: Add 6 electrons to the left side to balance the reduction half-reaction
Explanation: To balance the reduction half-reaction, 6 electrons are added to the left side. This ensures that the number of electrons gained in the reduction of chromium is accounted for.
224. What is the oxidation state of sulfur in $H_2SO_4$ (sulfuric acid)?
ⓐ. +4
ⓑ. +6
ⓒ. +2
ⓓ. 0
Correct Answer: +6
Explanation: In sulfuric acid ($H_2SO_4$), oxygen has an oxidation state of -2, and hydrogen has an oxidation state of +1. To balance the charge, sulfur must have an oxidation state of +6, as the sum of the oxidation numbers of all atoms must equal 0.
225. In the reaction $MnO_4^- + 8H^+ + 5e^- \rightarrow Mn^{2+} + 4H_2O$, what is the role of hydrogen ions ($H^+$)?
ⓐ. They balance the charge
ⓑ. They are oxidized
ⓒ. They are reduced
ⓓ. They act as a catalyst
Correct Answer: They balance the charge
Explanation: Hydrogen ions ($H^+$) are added to the left side of the equation to balance the charge. The addition of hydrogen ions ensures that the total charge on both sides of the reaction is equal.
226. What is the first step in balancing redox reactions using the ion-electron method (half-reaction method)?
ⓐ. Add electrons to balance the charge
ⓑ. Split the reaction into oxidation and reduction half-reactions
ⓒ. Balance the number of atoms on both sides
ⓓ. Multiply the half-reactions to balance the electrons
Correct Answer: Split the reaction into oxidation and reduction half-reactions
Explanation: The first step in the ion-electron method is to separate the redox reaction into two half-reactions: one for oxidation and one for reduction. This helps focus on balancing each process individually before combining them back together.
227. When balancing a redox reaction in acidic medium using the ion-electron method, which of the following is added to balance oxygen atoms?
ⓐ. Electrons
ⓑ. Hydrogen ions ($H^+$)
ⓒ. Hydroxide ions ($OH^-$)
ⓓ. Water molecules ($H_2O$)
Correct Answer: Water molecules ($H_2O$)
Explanation: In acidic medium, water molecules ($H_2O$) are added to balance oxygen atoms. Since acidic conditions provide $H^+$ ions, water molecules help adjust the oxygen atoms in the reaction.
228. When balancing a redox reaction in basic medium using the ion-electron method, what is added to balance hydrogen atoms?
ⓐ. Hydroxide ions ($OH^-$)
ⓑ. Electrons
ⓒ. Water molecules ($H_2O$)
ⓓ. Hydrogen ions ($H^+$)
Correct Answer: Hydroxide ions ($OH^-$)
Explanation: In basic medium, hydroxide ions ($OH^-$) are added to balance hydrogen atoms. In basic solutions, $OH^-$ is used instead of $H^+$ to maintain balance between both sides of the reaction.
229. In the reaction $MnO_4^- + 8H^+ + 5e^- \rightarrow Mn^{2+} + 4H_2O$, what is the oxidation number of manganese before and after the reaction?
ⓐ. +2 before, +7 after
ⓑ. +3 before, +5 after
ⓒ. 0 before, +2 after
ⓓ. +7 before, +2 after
Correct Answer: +7 before, +2 after
Explanation: In the permanganate ion ($MnO_4^-$), manganese has an oxidation number of +7. After the reaction, manganese is reduced to the $Mn^{2+}$ ion, where the oxidation number is +2. This shows a reduction of manganese from +7 to +2.
230. How do you balance a redox reaction using the ion-electron method in acidic medium?
ⓐ. First balance the oxidation states, then balance the charges with $H^+$ ions
ⓑ. Balance the atoms first, then add electrons to balance the charges
ⓒ. Balance the number of electrons first, then adjust the atoms
ⓓ. Add water molecules to balance both atoms and charges
Correct Answer: Balance the atoms first, then add electrons to balance the charges
Explanation: In the ion-electron method, you first balance the atoms in both half-reactions. Then, electrons are added to balance the charges on both sides of the reaction, ensuring conservation of charge.
231. In the reaction $2MnO_4^- + 16H^+ + 10e^- \rightarrow 2Mn^{2+} + 8H_2O$, what is the role of $H^+$ ions?
ⓐ. To balance the charge of the reaction
ⓑ. To balance the number of oxygen atoms
ⓒ. To balance the number of manganese atoms
ⓓ. To provide electrons for the reaction
Correct Answer: To balance the charge of the reaction
Explanation: In this reaction, $H^+$ ions are added to balance the charge of the reaction. Since manganese is being reduced from +7 to +2, the addition of $H^+$ ensures that both sides of the reaction are electrically balanced.
232. In the reaction $Cu^{2+} + 2e^- \rightarrow Cu$, how do you balance the charge?
ⓐ. By adding hydroxide ions ($OH^-$)
ⓑ. By adding $H^+$ ions
ⓒ. By adding water molecules ($H_2O$)
ⓓ. By adding electrons
Correct Answer: By adding electrons
Explanation: In this reaction, the copper ion ($Cu^{2+}$) is reduced to copper metal ($Cu$) by gaining two electrons. The electrons are added to balance the charge between the left and right sides of the equation.
233. Which of the following is the correct order of steps for balancing a redox reaction in acidic medium using the ion-electron method?
ⓐ. Assign oxidation numbers, balance atoms, balance charges with $H^+$, balance electrons, combine half-reactions
ⓑ. Assign oxidation numbers, balance charges with $OH^-$, balance electrons, balance atoms, combine half-reactions
ⓒ. Balance electrons, balance atoms, combine half-reactions, balance charges with $H^+$
ⓓ. Balance atoms, combine half-reactions, balance electrons, balance charges with $H^+$
Correct Answer: Assign oxidation numbers, balance atoms, balance charges with $H^+$, balance electrons, combine half-reactions
Explanation: In the ion-electron method, you first assign oxidation numbers to determine which elements are oxidized and reduced. Then, you balance the atoms, balance the charges using $H^+$ (in acidic medium), add electrons to balance the changes in oxidation states, and finally combine the half-reactions.
234. In the reaction $Cr_2O_7^{2-} + 14H^+ + 6e^- \rightarrow 2Cr^{3+} + 7H_2O$, how do you balance the oxygen atoms?
ⓐ. By adding electrons
ⓑ. By adding water molecules ($H_2O$)
ⓒ. By adding $OH^-$ ions
ⓓ. By adding $H^+$ ions
Correct Answer: By adding water molecules ($H_2O$)
Explanation: To balance the oxygen atoms in acidic medium, water molecules are added. In this reaction, the 7 oxygen atoms from $Cr_2O_7^{2-}$ are balanced by adding 7 molecules of water ($H_2O$) to the right side of the equation.
235. In the half-reaction $2H_2O + 2e^- \rightarrow H_2 + 2OH^-$, what is the role of electrons?
ⓐ. To balance the oxygen atoms
ⓑ. To balance the hydrogen atoms
ⓒ. To balance the charges on both sides
ⓓ. To balance the number of molecules
Correct Answer: To balance the charges on both sides
Explanation: In this half-reaction, electrons are added to balance the charge. On the left side, the charge is +2 (from $H_2O$), and on the right side, the charge is 0 (from $H_2$ and $OH^-$). The addition of electrons ensures that both sides have equal charges.
236. When balancing a redox reaction in acidic medium using the ion-electron method, what is the final step after balancing the half-reactions?
ⓐ. Add $OH^-$ ions to both sides
ⓑ. Add $H^+$ ions to both sides
ⓒ. Multiply the half-reactions by appropriate factors
ⓓ. Combine the half-reactions and balance the overall equation
Correct Answer: Combine the half-reactions and balance the overall equation
Explanation: After balancing the individual half-reactions in terms of atoms and charges, the final step is to combine the half-reactions. This involves ensuring that the number of electrons lost in oxidation equals the number of electrons gained in reduction, and adjusting the coefficients to balance the overall equation.
237. In the reaction $2Fe^{3+} + 3e^- \rightarrow 2Fe^{2+}$, how do you balance the charges?
ⓐ. By adding electrons to the right side
ⓑ. By adding $H^+$ ions
ⓒ. By adding electrons to the left side
ⓓ. By adding $OH^-$ ions
Correct Answer: By adding electrons to the left side
Explanation: In this reduction half-reaction, $Fe^{3+}$ is reduced to $Fe^{2+}$ by gaining electrons. To balance the charges on both sides of the equation, 3 electrons are added to the left side.
238. What is the main purpose of the ion-electron method in balancing redox reactions?
ⓐ. To identify the products of the reaction
ⓑ. To ensure the reaction is balanced in terms of both atoms and charge
ⓒ. To calculate the energy released in the reaction
ⓓ. To determine the type of reaction (acidic or basic)
Correct Answer: To ensure the reaction is balanced in terms of both atoms and charge
Explanation: The ion-electron method ensures that the redox reaction is balanced in terms of both the number of atoms and the total charge. It involves splitting the reaction into oxidation and reduction half-reactions, balancing them, and then combining them to form the overall balanced equation.
239. What is the primary purpose of cellular respiration in organisms?
ⓐ. To store energy
ⓑ. To produce oxygen
ⓒ. To produce glucose
ⓓ. To convert glucose into usable energy (ATP)
Correct Answer: To convert glucose into usable energy (ATP)
Explanation: The primary purpose of cellular respiration is to convert glucose into usable energy in the form of ATP, which cells use to perform various functions. Cellular respiration occurs in three stages: glycolysis, the citric acid cycle, and oxidative phosphorylation.
240. Where does glycolysis occur in a cell?
ⓐ. Mitochondria
ⓑ. Cytoplasm
ⓒ. Nucleus
ⓓ. Chloroplast
Correct Answer: Cytoplasm
Explanation: Glycolysis is the first step in cellular respiration and occurs in the cytoplasm of the cell. During glycolysis, glucose is broken down into two molecules of pyruvate, producing a small amount of ATP and NADH.
241. What is the end product of the citric acid cycle (Krebs cycle)?
ⓐ. ATP
ⓑ. Glucose
ⓒ. Oxygen
ⓓ. NADH and FADH2
Correct Answer: NADH and FADH2
Explanation: The citric acid cycle (also known as the Krebs cycle) generates high-energy molecules, NADH and FADH2, which carry electrons to the electron transport chain. It also produces a small amount of ATP and releases carbon dioxide as a waste product.
242. Which molecule is the final electron acceptor in the electron transport chain during cellular respiration?
ⓐ. Oxygen
ⓑ. Carbon dioxide
ⓒ. Glucose
ⓓ. NADH
Correct Answer: Oxygen
Explanation: In the electron transport chain, oxygen serves as the final electron acceptor. It combines with electrons and hydrogen ions to form water. This step is critical in the production of a large amount of ATP during cellular respiration.
243. Which of the following occurs during the process of photosynthesis?
ⓐ. Light energy is converted into chemical energy
ⓑ. Oxygen is consumed as a reactant
ⓒ. Carbon dioxide is released into the atmosphere
ⓓ. ATP is used to break down glucose
Correct Answer: Light energy is converted into chemical energy
Explanation: During photosynthesis, light energy is absorbed by chlorophyll and other pigments in the chloroplasts and is converted into chemical energy in the form of glucose. Oxygen is released as a byproduct of photosynthesis, not consumed.
244. Where does the light-dependent reaction of photosynthesis take place?
ⓐ. Mitochondria
ⓑ. Stroma
ⓒ. Thylakoid membranes
ⓓ. Cytoplasm
Correct Answer: Thylakoid membranes
Explanation: The light-dependent reactions of photosynthesis occur in the thylakoid membranes of the chloroplasts. These reactions use light energy to produce ATP and NADPH, which are later used in the light-independent reactions (Calvin cycle) to produce glucose.
245. What is the main function of the Calvin cycle in photosynthesis?
ⓐ. To produce oxygen
ⓑ. To convert glucose into ATP
ⓒ. To synthesize glucose from carbon dioxide
ⓓ. To generate NADPH
Correct Answer: To synthesize glucose from carbon dioxide
Explanation: The Calvin cycle is the light-independent reaction of photosynthesis, where carbon dioxide is fixed into a 3-carbon sugar, eventually forming glucose. The cycle uses ATP and NADPH produced in the light-dependent reactions.
246. In cellular respiration, what is the primary role of oxygen?
ⓐ. To produce glucose
ⓑ. To accept electrons at the end of the electron transport chain
ⓒ. To convert glucose into pyruvate
ⓓ. To release energy in the form of ATP
Correct Answer: To accept electrons at the end of the electron transport chain
Explanation: Oxygen acts as the final electron acceptor in the electron transport chain during cellular respiration. It combines with electrons and hydrogen ions to form water, a critical step for the production of ATP.
247. What is the process of anaerobic respiration?
ⓐ. Respiration that occurs in the presence of oxygen
ⓑ. Photosynthesis in the absence of light
ⓒ. The breakdown of glucose to form ATP only in the mitochondria
ⓓ. Respiration that occurs without oxygen, producing lactic acid or ethanol
Correct Answer: Respiration that occurs without oxygen, producing lactic acid or ethanol
Explanation: Anaerobic respiration occurs when oxygen is not available. In animals, it produces lactic acid, and in yeast or plants, it produces ethanol and carbon dioxide. This process is less efficient than aerobic respiration in terms of ATP production.
248. Which of the following is produced during the light-dependent reactions of photosynthesis?
ⓐ. Glucose
ⓑ. NADP+
ⓒ. Carbon dioxide
ⓓ. Oxygen
Correct Answer: Oxygen
Explanation: During the light-dependent reactions of photosynthesis, water molecules are split, releasing oxygen as a byproduct. The light energy is used to produce ATP and NADPH, which are then used in the Calvin cycle.
249. Which of the following statements about the electron transport chain in cellular respiration is true?
ⓐ. It occurs in the cytoplasm of the cell
ⓑ. It produces glucose from carbon dioxide
ⓒ. It generates a large amount of ATP through oxidative phosphorylation
ⓓ. It does not require oxygen to function
Correct Answer: It generates a large amount of ATP through oxidative phosphorylation
Explanation: The electron transport chain takes place in the inner mitochondrial membrane and generates a large amount of ATP through oxidative phosphorylation. Oxygen is required as the final electron acceptor to form water and enable ATP production.
250. What is the role of NADPH in photosynthesis?
ⓐ. To store light energy
ⓑ. To carry electrons to the Calvin cycle
ⓒ. To break down glucose
ⓓ. To release energy for the electron transport chain
Correct Answer: To carry electrons to the Calvin cycle
Explanation: NADPH is produced during the light-dependent reactions of photosynthesis and carries electrons to the Calvin cycle, where they are used to reduce carbon dioxide into glucose.
251. In glycolysis, what is the end product of the breakdown of glucose?
ⓐ. Pyruvate
ⓑ. Acetyl-CoA
ⓒ. Lactic acid
ⓓ. Oxygen
Correct Answer: Pyruvate
Explanation: During glycolysis, one molecule of glucose (6 carbon atoms) is broken down into two molecules of pyruvate (3 carbon atoms each), along with a small amount of ATP and NADH. This process occurs in the cytoplasm.
252. What is the name of the cycle that produces most of the ATP in cellular respiration?
ⓐ. Citric acid cycle
ⓑ. Calvin cycle
ⓒ. Glycolysis
ⓓ. Electron transport chain
Correct Answer: Electron transport chain
Explanation: The electron transport chain produces most of the ATP in cellular respiration. It occurs in the inner mitochondrial membrane and generates ATP by oxidative phosphorylation using electrons from NADH and FADH2.
253. What is the final product of anaerobic respiration in muscles?
ⓐ. Lactic acid
ⓑ. Glucose
ⓒ. Ethanol
ⓓ. Acetyl-CoA
Correct Answer: Lactic acid
Explanation: In muscles, during anaerobic respiration (in the absence of oxygen), glucose is partially broken down into lactic acid. This process provides a small amount of ATP but is less efficient than aerobic respiration.
254. In photosynthesis, what is the function of chlorophyll?
ⓐ. To produce glucose
ⓑ. To absorb light energy and initiate the light-dependent reactions
ⓒ. To release oxygen during the light-independent reactions
ⓓ. To transport carbon dioxide to the Calvin cycle
Correct Answer: To absorb light energy and initiate the light-dependent reactions
Explanation: Chlorophyll absorbs light energy from the sun and plays a crucial role in initiating the light-dependent reactions of photosynthesis. This energy is then used to produce ATP and NADPH for the Calvin cycle.
255. What is the primary source of energy for plants during photosynthesis?
ⓐ. Oxygen
ⓑ. Carbon dioxide
ⓒ. Light energy from the sun
ⓓ. Water
Correct Answer: Light energy from the sun
Explanation: The primary source of energy for photosynthesis is light energy from the sun. This energy is absorbed by chlorophyll and other pigments in the plant, which is then used to produce glucose and oxygen.
256. How many molecules of ATP are produced in aerobic respiration for every molecule of glucose?
ⓐ. 2
ⓑ. 10
ⓒ. 36
ⓓ. 1
Correct Answer: 36
Explanation: In aerobic respiration, approximately 36 molecules of ATP are produced for every molecule of glucose, which is much more efficient than anaerobic respiration, which produces only 2 ATP molecules per glucose.
257. In cellular respiration, which molecule is the primary electron carrier?
ⓐ. ATP
ⓑ. NADH
ⓒ. FADH2
ⓓ. Oxygen
Correct Answer: NADH
Explanation: NADH is the primary electron carrier in cellular respiration. It carries electrons from glycolysis and the citric acid cycle to the electron transport chain, where they are used to generate ATP.
258. What is the main cause of the rusting of iron?
ⓐ. Reaction with carbon dioxide
ⓑ. Reaction with oxygen and water
ⓒ. Reaction with sulfur
ⓓ. Reaction with chlorine
Correct Answer: Reaction with oxygen and water
Explanation: Rusting of iron occurs when iron reacts with oxygen in the presence of water or moisture, forming iron oxide ($Fe_2O_3$), which is commonly known as rust. This is a type of corrosion reaction that damages the metal.
259. Which of the following is the correct chemical formula for rust?
ⓐ. $Fe_2O_3$
ⓑ. $Fe_3O_4$
ⓒ. $FeO$
ⓓ. $Fe_2O_3\cdot H_2O$
Correct Answer: $Fe_2O_3\cdot H_2O$
Explanation: Rust is a hydrated form of iron oxide, often represented as $Fe_2O_3\cdot H_2O$. This is a combination of iron oxide and water, which forms when iron reacts with oxygen and moisture.
260. What is the primary chemical reaction involved in the rusting of iron?
ⓐ. $2Fe + 3O_2 + 6H_2O \rightarrow 2Fe(OH)_3$
ⓑ. $Fe + 2O_2 \rightarrow FeO_2$
ⓒ. $Fe + 3O_2 \rightarrow Fe_3O_4$
ⓓ. $Fe + 2H_2O \rightarrow Fe(OH)_2$
Correct Answer: $2Fe + 3O_2 + 6H_2O \rightarrow 2Fe(OH)_3$
Explanation: The primary chemical reaction in the rusting of iron involves the reaction of iron with oxygen and water to form iron(III) hydroxide ($Fe(OH)_3$), which then dehydrates to form iron oxide ($Fe_2O_3$), or rust.
261. Which of the following conditions accelerates the rusting of iron?
ⓐ. Dry conditions
ⓑ. Exposure to carbon dioxide
ⓒ. Presence of saltwater
ⓓ. Lack of oxygen
Correct Answer: Presence of saltwater
Explanation: Saltwater accelerates the rusting of iron because the salt (sodium chloride) increases the conductivity of water, making it easier for electrons to transfer during the corrosion process. This speeds up the rusting of iron.
262. What is the role of water in the rusting of iron?
ⓐ. Water provides oxygen
ⓑ. Water acts as a solvent for iron oxide
ⓒ. Water allows for the transport of electrons
ⓓ. Water prevents rust formation
Correct Answer: Water allows for the transport of electrons
Explanation: Water plays an essential role in the rusting of iron by acting as an electrolyte, allowing electrons to move between the iron surface and oxygen. This facilitates the redox reactions that lead to the formation of rust.
263. What is the protective layer that forms on iron during the corrosion process called?
ⓐ. Iron oxide
ⓑ. Zinc coating
ⓒ. Iron hydroxide
ⓓ. Rust
Correct Answer: Iron oxide
Explanation: The protective layer that forms on iron during corrosion is iron oxide ($Fe_2O_3$), commonly known as rust. However, this layer does not always prevent further corrosion, as it can flake off, exposing fresh metal to moisture and oxygen.
264. Which of the following can be used to prevent the rusting of iron?
ⓐ. Galvanization (coating with zinc)
ⓑ. Exposing iron to sunlight
ⓒ. Increasing the temperature
ⓓ. Adding more oxygen to the air
Correct Answer: Galvanization (coating with zinc)
Explanation: Galvanization involves coating iron with zinc to protect it from rusting. Zinc acts as a sacrificial metal that corrodes instead of the iron, preventing the iron from coming into contact with oxygen and water.
265. What type of reaction occurs during the rusting of iron?
ⓐ. Oxidation
ⓑ. Reduction
ⓒ. Neutralization
ⓓ. Sublimation
Correct Answer: Oxidation
Explanation: Rusting is an oxidation reaction where iron loses electrons to oxygen and water, forming iron oxide. The iron is oxidized, while oxygen is reduced during the corrosion process.
266. What is the common name for iron oxide formed during rusting?
ⓐ. Ferrite
ⓑ. Rust
ⓒ. Copper oxide
ⓓ. Lime
Correct Answer: Rust
Explanation: The common name for iron oxide formed during rusting is rust. Rust is a mixture of iron oxides, primarily iron(III) oxide ($Fe_2O_3$), which forms when iron reacts with oxygen and water over time.
267. Which of the following is NOT a factor that contributes to the rusting of iron?
ⓐ. High humidity
ⓑ. Presence of saltwater
ⓒ. Exposure to carbon dioxide
ⓓ. High temperature
Correct Answer: Exposure to carbon dioxide
Explanation: Carbon dioxide does not directly contribute to the rusting of iron. Factors such as high humidity, presence of saltwater, and high temperature can accelerate the rusting process by providing the necessary conditions for the redox reactions.
268. In the rusting process, what happens to iron atoms?
ⓐ. They gain electrons
ⓑ. They lose electrons
ⓒ. They remain unaffected
ⓓ. They combine with water
Correct Answer: They lose electrons
Explanation: During the rusting of iron, iron atoms lose electrons in the oxidation process. These electrons are transferred to oxygen, which is reduced to form hydroxide ions, leading to the formation of iron oxide (rust).
269. Which metal is commonly used to prevent rusting through galvanization?
ⓐ. Copper
ⓑ. Lead
ⓒ. Tin
ⓓ. Zinc
Correct Answer: Zinc
Explanation: Zinc is commonly used to prevent rusting through galvanization, a process where a layer of zinc is applied to iron. Zinc acts as a sacrificial metal, corroding in place of the iron, thereby protecting it from rust.
270. Which of the following is a consequence of iron rusting?
ⓐ. Iron becomes stronger and harder
ⓑ. The iron is converted into a different metal
ⓒ. The iron loses its original properties and strength
ⓓ. Iron is converted into a gas
Correct Answer: The iron loses its original properties and strength
Explanation: Rusting weakens iron by converting it into a brittle form of iron oxide, which has less strength and durability than pure iron. This is one of the major consequences of rusting.
271. Which of the following factors can slow down the rusting process of iron?
ⓐ. Increasing humidity
ⓑ. Coating the iron with paint
ⓒ. Exposing the iron to saltwater
ⓓ. Increasing temperature
Correct Answer: Coating the iron with paint
Explanation: Coating iron with paint or other protective coatings, such as oil or lacquer, can slow down or prevent rusting by providing a barrier that prevents water and oxygen from reaching the iron surface.
272. What is the role of oxygen in the rusting of iron?
ⓐ. Oxygen acts as a reducing agent
ⓑ. Oxygen reacts with water to form hydroxide ions
ⓒ. Oxygen oxidizes the iron directly
ⓓ. Oxygen prevents rust from forming
Correct Answer: Oxygen oxidizes the iron directly
Explanation: In the rusting of iron, oxygen acts as the oxidizing agent, accepting electrons from iron and causing the iron to oxidize. This leads to the formation of iron oxide, or rust.
273. What happens to the iron atoms during the formation of rust?
ⓐ. They are reduced
ⓑ. They form new metals
ⓒ. They become part of the water molecules
ⓓ. They are oxidized
Correct Answer: They are oxidized
Explanation: During the rusting process, iron atoms are oxidized. They lose electrons to oxygen, which leads to the formation of iron oxides (rust).
274. Which of the following is the correct reaction for the rusting of iron in the presence of oxygen and water?
ⓐ. $Fe + O_2 \rightarrow FeO$
ⓑ. $2Fe + 3O_2 + 2H_2O \rightarrow 2Fe(OH)_2$
ⓒ. $4Fe + 3O_2 + 6H_2O \rightarrow 4Fe(OH)_3$
ⓓ. $Fe + 2O_2 \rightarrow Fe_2O_3$
Correct Answer: $4Fe + 3O_2 + 6H_2O \rightarrow 4Fe(OH)_3$
Explanation: The rusting of iron involves the reaction of iron with oxygen and water, producing iron(III) hydroxide ($Fe(OH)_3$), which dehydrates to form iron oxide (rust). The correct equation is $4Fe + 3O_2 + 6H_2O \rightarrow 4Fe(OH)_3$.
275. What is the role of electrons in the rusting of iron?
ⓐ. Electrons are lost by oxygen
ⓑ. Electrons are gained by iron
ⓒ. Electrons are transferred to the metal from water
ⓓ. Electrons are not involved in the rusting process
Correct Answer: Electrons are gained by iron
Explanation: In the rusting of iron, iron loses electrons (oxidation) and is converted into iron ions. Oxygen gains these electrons (reduction), allowing the formation of iron oxide, or rust. Therefore, iron gains electrons during the process.
276. What is the primary role of an oxidizing agent in the bleaching process?
ⓐ. To absorb light energy
ⓑ. To increase the color intensity
ⓒ. To reduce the color of a substance
ⓓ. To break chemical bonds in pigments
Correct Answer: To break chemical bonds in pigments
Explanation: In bleaching, an oxidizing agent breaks the chemical bonds in the pigment molecules, which removes the color. This process effectively “decolorizes” the substance being bleached.
277. Which of the following is commonly used as an oxidizing agent for bleaching?
ⓐ. Hydrogen peroxide
ⓑ. Sodium chloride
ⓒ. Sodium hydroxide
ⓓ. Ammonia
Correct Answer: Hydrogen peroxide
Explanation: Hydrogen peroxide ($H_2O_2$) is commonly used as an oxidizing agent for bleaching because it can break down complex organic pigments and decolorize them by providing oxygen during the reaction.
278. How does chlorine bleach work as an oxidizing agent?
ⓐ. It reduces the pigments
ⓑ. It releases oxygen and breaks the chemical bonds in pigments
ⓒ. It adds hydrogen to the pigments
ⓓ. It increases the color of the pigment
Correct Answer: It releases oxygen and breaks the chemical bonds in pigments
Explanation: Chlorine bleach works as an oxidizing agent by releasing oxygen, which attacks the chemical bonds in pigments. This process breaks down the molecules responsible for color, thereby bleaching the material.
279. What is the main difference between bleaching with chlorine and bleaching with hydrogen peroxide?
ⓐ. Chlorine acts by reducing the pigments, while hydrogen peroxide oxidizes them
ⓑ. Chlorine is a reducing agent, and hydrogen peroxide is an oxidizing agent
ⓒ. Chlorine releases chlorine gas, whereas hydrogen peroxide releases oxygen
ⓓ. Hydrogen peroxide acts as a disinfectant, while chlorine is only for coloring removal
Correct Answer: Chlorine releases chlorine gas, whereas hydrogen peroxide releases oxygen
Explanation: Chlorine bleach releases chlorine gas as an oxidizing agent, while hydrogen peroxide releases oxygen, which is used to break down pigments. Both serve as bleaching agents, but they do so via different mechanisms.
280. What is one of the main uses of bleaching powder (Ca(OCl)2)?
ⓐ. As a reducing agent in chemical reactions
ⓑ. As a disinfectant and for water treatment
ⓒ. As a colorant in food products
ⓓ. To increase the acidity of solutions
Correct Answer: As a disinfectant and for water treatment
Explanation: Bleaching powder (calcium hypochlorite, $Ca(OCl)_2$) is primarily used as a disinfectant and in water treatment to kill bacteria and other pathogens. It also serves as an oxidizing agent in bleaching applications.
281. Which of the following is a common industrial application of bleaching with oxidizing agents?
ⓐ. Bleaching textiles and paper
ⓑ. Cleaning glass surfaces
ⓒ. Neutralizing acids
ⓓ. Rust removal from metals
Correct Answer: Bleaching textiles and paper
Explanation: Oxidizing agents, such as chlorine and hydrogen peroxide, are widely used in the textile and paper industries to bleach fabrics and paper. These agents break down the colored compounds, resulting in a whiter product.
282. In the reaction where hydrogen peroxide is used as a bleaching agent, what is the main product after the oxidation of the pigment?
ⓐ. Water
ⓑ. Chlorine
ⓒ. Carbon dioxide
ⓓ. Oxygen
Correct Answer: Oxygen
Explanation: When hydrogen peroxide is used as a bleaching agent, it releases oxygen during the oxidation process. This oxygen breaks the chemical bonds in pigments, leading to the removal of color.
283. Which of the following oxidizing agents is used for bleaching hair?
ⓐ. Chlorine
ⓑ. Ozone
ⓒ. Potassium permanganate
ⓓ. Hydrogen peroxide
Correct Answer: Hydrogen peroxide
Explanation: Hydrogen peroxide is commonly used for bleaching hair. It works by oxidizing the melanin in hair, which reduces the color and lightens the hair.
284. How does sodium hypochlorite ($NaOCl$) bleach clothes?
ⓐ. By adding hydrogen to the pigments
ⓑ. By releasing oxygen to break the chemical bonds of the pigments
ⓒ. By directly reacting with the fabric fibers
ⓓ. By dissolving the pigments in water
Correct Answer: By releasing oxygen to break the chemical bonds of the pigments
Explanation: Sodium hypochlorite ($NaOCl$) works as an oxidizing agent in bleaching by releasing oxygen, which breaks the chemical bonds in the pigments, removing the color from the fabric.
285. What is the role of oxygen in bleaching with oxidizing agents like hydrogen peroxide?
ⓐ. It adds hydrogen to the pigments
ⓑ. It reacts with water to form hydroxide ions
ⓒ. It breaks down the bonds in the pigment molecules
ⓓ. It enhances the color intensity of the pigment
Correct Answer: It breaks down the bonds in the pigment molecules
Explanation: Oxygen released by oxidizing agents like hydrogen peroxide reacts with the bonds in pigment molecules, breaking them down and effectively decolorizing the material being treated.
286. In the bleaching of paper, which of the following is the role of chlorine dioxide ($ClO_2$)?
ⓐ. It reduces the pigment molecules
ⓑ. It acts as an oxidizing agent to bleach the paper
ⓒ. It dissolves the paper fibers
ⓓ. It adds color to the paper
Correct Answer: It acts as an oxidizing agent to bleach the paper
Explanation: Chlorine dioxide ($ClO_2$) is used as a bleaching agent in the paper industry. It acts as an oxidizing agent that breaks down the organic pigments and decolorizes the paper.
287. Why is hydrogen peroxide considered a safer alternative to chlorine for bleaching purposes?
ⓐ. It is non-toxic and does not release harmful gases
ⓑ. It has a stronger bleaching effect
ⓒ. It works faster than chlorine
ⓓ. It is more efficient in removing tough stains
Correct Answer: It is non-toxic and does not release harmful gases
Explanation: Hydrogen peroxide is considered a safer alternative to chlorine because it is non-toxic and does not release harmful gases, such as chlorine gas, during the bleaching process. It also decomposes into water and oxygen, making it environmentally friendly.
288. Which of the following is NOT a common application of oxidizing agents in bleaching?
ⓐ. Bleaching of textiles
ⓑ. Bleaching of teeth
ⓒ. Bleaching of food products
ⓓ. Bleaching of metals
Correct Answer: Bleaching of metals
Explanation: Oxidizing agents are not typically used to bleach metals. They are more commonly used in the bleaching of textiles, food products, and teeth, but not metals. Metals may undergo corrosion or rusting, but not bleaching in the same sense as fabrics or paper.
289. How do oxidizing agents like chlorine and hydrogen peroxide affect the chemical structure of colored compounds?
ⓐ. They stabilize the colored compounds
ⓑ. They break down the bonds responsible for color
ⓒ. They add new bonds to enhance the color
ⓓ. They change the pH of the compound
Correct Answer: They break down the bonds responsible for color
Explanation: Oxidizing agents like chlorine and hydrogen peroxide break down the chemical bonds in the pigment molecules, which are responsible for color. This decolorizes the substance by disrupting the conjugated systems of the pigment molecules.
290. Which of the following oxidizing agents is commonly used in household bleach?
ⓐ. Hydrogen chloride
ⓑ. Hydrogen peroxide
ⓒ. Sodium hypochlorite
ⓓ. Potassium dichromate
Correct Answer: Sodium hypochlorite
Explanation: Sodium hypochlorite ($NaOCl$) is the active ingredient in most household bleach products. It is a strong oxidizing agent that is effective for cleaning and bleaching purposes.
291. What is the primary source of energy production in cells?
ⓐ. Oxygen
ⓑ. Glucose
ⓒ. Nitrogen
ⓓ. Fatty acids
Correct Answer: Glucose
Explanation: The primary source of energy production in cells is glucose. Through processes like glycolysis, the citric acid cycle, and oxidative phosphorylation, glucose is broken down to produce ATP, the energy currency of the cell.
292. Where does glycolysis occur in the cell?
ⓐ. Mitochondria
ⓑ. Nucleus
ⓒ. Cytoplasm
ⓓ. Endoplasmic reticulum
Correct Answer: Cytoplasm
Explanation: Glycolysis, the first step in cellular respiration, occurs in the cytoplasm. It involves the breakdown of glucose into pyruvate, producing a small amount of ATP and NADH.
293. Which of the following is the final electron acceptor in the electron transport chain during cellular respiration?
ⓐ. Carbon dioxide
ⓑ. Glucose
ⓒ. Oxygen
ⓓ. NADH
Correct Answer: Oxygen
Explanation: Oxygen is the final electron acceptor in the electron transport chain during cellular respiration. It combines with electrons and hydrogen ions to form water, a critical step for the production of ATP.
294. What is the main product of the citric acid cycle (Krebs cycle)?
ⓐ. Glucose
ⓑ. Oxygen
ⓒ. Carbon dioxide
ⓓ. ATP and electron carriers (NADH, FADH2)
Correct Answer: ATP and electron carriers (NADH, FADH2)
Explanation: The citric acid cycle produces ATP, NADH, and FADH2. These electron carriers carry high-energy electrons to the electron transport chain, where most of the ATP is generated.
295. What is the role of NADH and FADH2 in cellular respiration?
ⓐ. To provide energy directly for the cell
ⓑ. To transport electrons to the electron transport chain
ⓒ. To break down glucose
ⓓ. To produce oxygen
Correct Answer: To transport electrons to the electron transport chain
Explanation: NADH and FADH2 are electron carriers that transport high-energy electrons to the electron transport chain, where they are used to generate a large amount of ATP.
296. How many molecules of ATP are produced from one molecule of glucose during aerobic respiration?
ⓐ. 2
ⓑ. 10
ⓒ. 0
ⓓ. 36
Correct Answer: 36
Explanation: In aerobic respiration, approximately 36 ATP molecules are produced from one molecule of glucose, with most of the ATP generated during the electron transport chain and oxidative phosphorylation.
297. In the absence of oxygen, what process do cells use to generate energy?
ⓐ. Photosynthesis
ⓑ. Glycolysis
ⓒ. Fermentation
ⓓ. Citric acid cycle
Correct Answer: Fermentation
Explanation: In the absence of oxygen, cells rely on fermentation to generate ATP. Fermentation occurs after glycolysis and produces either lactic acid (in animals) or ethanol and carbon dioxide (in yeast), along with a small amount of ATP.
298. What is the final product of anaerobic respiration in muscles?
ⓐ. Lactic acid
ⓑ. Glucose
ⓒ. Oxygen
ⓓ. Acetyl-CoA
Correct Answer: Lactic acid
Explanation: In muscles, during anaerobic respiration (in the absence of oxygen), glucose is partially broken down into lactic acid. This process provides a small amount of ATP but is less efficient than aerobic respiration.
299. In which part of the cell does oxidative phosphorylation take place?
ⓐ. Cytoplasm
ⓑ. Mitochondrial matrix
ⓒ. Inner mitochondrial membrane
ⓓ. Nucleus
Correct Answer: Inner mitochondrial membrane
Explanation: Oxidative phosphorylation takes place in the inner mitochondrial membrane. It involves the electron transport chain and chemiosmosis, leading to the production of a large amount of ATP.
300. Which of the following processes occurs in the mitochondria and produces the most ATP?
ⓐ. Glycolysis
ⓑ. Citric acid cycle
ⓒ. Electron transport chain
ⓓ. Fermentation
Correct Answer: Electron transport chain
Explanation: The electron transport chain, located in the inner mitochondrial membrane, produces the most ATP in cellular respiration. It uses high-energy electrons from NADH and FADH2 to generate ATP through oxidative phosphorylation.
Welcome to Class 11 Chemistry MCQs – Chapter 8: Redox Reactions (Part 3). This set of 100 MCQs focuses on the balancing of redox equations, ion-electron method, and oxidation-number method. Each question helps you build accuracy and speed for Board exams and JEE/NEET.
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- 👉 Total MCQs in chapter: 376 (100 + 100 + 100 + 76)
- 👉 This page: Third set of 100 solved MCQs
- 👉 Next: Go to Part 4 for the final set