Some Basic Concepts of Chemistry Mock Test – Class 11 Chemistry

1. A sample has mass and volume . Using , how should the density be reported?

2. In a back-calculation, of is obtained from of a solution containing . If , the molarity of in the original solution is:

3. A postulate says that atoms of the same element are identical in mass and properties, while atoms of different elements differ. In modern chemistry, this statement is modified mainly because:

4. A liquid mixture contains of ethanol in of solution. The volume percentage of ethanol is:

5. Assertion: A gas does not have a fixed volume of its own under ordinary conditions.
Reason: Gas particles are far apart and move freely, so they spread through the available space.

6. The value is less clear in significant figures than because:

7. A student says, "The reactant with the smaller mass is always the limiting reagent." The best correction is:

8. In a multi-step calculation, a student gets an intermediate value but the final answer must be reported to significant figures. The best practice is to:

9. The final volume after mixing of with of water is . The final concentration of is:

10. A solution contains of . It is diluted to . The final molarity is:

11. Study the table below for empirical formula work.

The step that needs correction is:

12. A shiny grey solid conducts electricity, has density , and slowly rusts in moist air. Which entry is a chemical property?

13. A sample of is diluted to . After dilution, the concentration of ions is:

14. The volume relation is useful because:

15. A compound has formula . The total number of oxygen atoms in one formula unit is:

16. A solution of is completely dissociated. The concentration of total ions in the solution is:

17. Use the graph description below.

The correct left-to-right order is:

18. A law statement says: "When two elements form more than one compound, the different masses of one element that combine with a fixed mass of the other are in small whole-number ratios." This statement is:

19. A dilute water sample contains an impurity at by mass. If the mass of the water sample is , the mass of impurity present is:

20. A solution is prepared by dissolving of in water and making the volume . If of this solution is taken, how many moles of does the aliquot contain? Use .

21. A mass is reported as . The final zero is significant mainly because:

22. A transparent liquid is made by mixing ethanol and water completely. No separate layer is seen. The absence of layers mainly shows that the sample is:

23. Consider these statements about solution stoichiometry:
I. Molarity can convert solution volume into moles of solute.
II. A balanced equation converts moles of one reacting substance into moles of another.
III. Mass of product can be found from product moles using molar mass.

24. A mixture of sand and water is shaken and then allowed to stand. The sand gradually settles at the bottom. This observation supports the idea that the sample is:

25. A sample of contains of molecules. The amount of hydrogen atoms in the sample is:

26. A concentration is written as . The same value in scientific notation with the same significant figures is:

27. Hydrogen and chlorine react as . If of is mixed with of at the same and , the volume of formed is:

28. Consider these statements about physical and chemical changes:
I. A physical change does not produce a new substance.
II. A chemical change produces one or more new substances.
III. Every reversible change must be chemical.

29. A thermometer is used to measure a liquid whose true temperature is . The readings are , , and . The best description is:

30. A calculator display shows . In scientific notation, this means:

31. A bottle of perfume is opened in one corner of a room, and after some time its smell is noticed across the room. This observation is mainly an example of:

32. A sample contains of . The total number of atoms present in the sample is:

33. A gas sample at contains molecules of . Its volume is:

34. A balance always shows even when nothing is placed on the pan. Masses measured without correcting this zero error are likely to have:

35. A sample of element X has isotope and isotope . What is the average atomic mass?

36. Assertion: A set of readings can be highly precise but poorly accurate.
Reason: Repeated readings may be close together even when an instrument has a constant calibration error.

37. Use the graph description below.

Use . The slope of the graph is:

38. The change from liquid water to water vapour is called:

39. Carbon and oxygen form and . For the same mass of carbon, the masses of oxygen that combine are in the ratio:

40. What is the mass of of , using molar mass ?

41. A solution of is mixed with excess . A portion produces . The moles of formed are:

42. A student mixes of with of . For , the amount of formed is:

43. Scientific notation writes a number in the form . For standard scientific notation, the coefficient should satisfy:

44. Match each concentration term in Column I with the correct denominator in Column II.

45. A by mass aqueous solution of glucose has total mass . What mass of water is present?

46. A particle diameter is recorded as . The same diameter in is:

47. A solution contains in . After complete dissociation, the concentration of ions is:

48. A sample of a compound contains carbon and oxygen by mass. Another pure sample of the same compound has mass . What mass of oxygen is present?

49. A student says, "In , the total ion concentration is because the solution has one salt concentration." The best correction is:

50. A pure substance is broken down by a chemical method into two simpler substances. The original substance is best described as: