Atoms And Molecules MCQs With Answer

Atoms And Molecules
Class:9 | Chapter:3

Multiple Choice Questions

1. Argon is
(a) Monoatomic
(b) Diatomic
(c) Tetraatomic
(d) Polyatomic

2. H₂O represents
(a) Water
(b) Hydrogen
(c) Oxygen
(d) Hydrogen peroxide

3. Formula for Aluminium oxide is
(a) AlO₃
(b) Al₃O
(c)Al₂O₃
(d) AlO₂

4. The molecular mass of C₂H₆ is
(a) 28
(b) 30
(c) 18
(d) 42

5. The molecule having an atomicity of 4 is
(a) Sulphate molecule
(b) Ozone molecule
(c) Phosphorus molecule
(d) Methane molecule

6. 1 u or 1 amu means
(a) 1/12th mass of C-12 atoms
(b) Mass of C-12 atom
(c) Mass of O-16 atom
(d) Mass of Hydrogen molecule

7. An element X is divalent and another element Y is tetravalent. The compound formed by these two elements will be:
(a) XY
(b) XY₂
(c) X₂Y
(d) XY₄

8. The atomic mass of sodium is 23. The number of moles in 92g of sodium is
(a) 4
(b) 2
(c) 0
(d) 1/2

9. 32 g Oxygen is
(a) 1 mole atoms
(b) 0.5 mole atoms
(c)1.5 mole atoms
(d) 2 mole atoms

10. The chloride of a metal has the formula MCl₃. The formula of it's phosphate will be
(a) M₂PO₄
(b) MPO₄
(c)M₃PO₄
(d) M(PO₄)₂

11. The chemical symbol for nitrogen gas is
(a) Ni
(b) N₂
(c) N⁺
(d) N

12. The chemical symbol for sodium is
(a) So
(b) Sd
(c) NA
(d) Na

13. Which of the following would weigh the highest?
(a) 0.2 mole of sucrose (C₁₂H₂₂O₁₁)
(b) 2 moles of CO₂
(c) 2 moles of CaCO₃
(d) 10 moles of H₂O

14. Which of the following has maximum number of atoms?
(a) 18 g of H₂O
(b) 18 g of O₂
(c) 18 g of CO₂
(d) 18 g of CO₄

15. Which of the following correctly represents 360 g of water?
(i) 2 moles of H₂O
(ii) 20 moles of water
(iii) 6.022 × 10²³ molecules of water
(iv) 1.2044 × 10²⁵ molecules of water
(a) (i)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)

16. 3.42 g of sucrose are dissolved in 18 g of water in a beaker. The number of oxygen atoms in the solution are
(a) 6.68 × 10²³
(b) 6.09 × 10²²
(c) 6.022 × 10²³
(d) 6.022 × 10²³

17. A change in the physical state can be brought about
(a) only when energy is given to the system
(b) only when energy is taken out from the system
(c) when energy is either given to, or taken out from the system
(d) without any energy change

18. The relative molecular mass of Na₂S₂O₃.5H₂O is
(a) 250 amu
(b) 250 g
(c) 248 amu
(d) 248 g

19. Which of the following has maximum number of atom?
(a) 18 g H₂O
(b) 18 g of O₂
(c) 18 g of CO₂
(d) 18 g of CH₄

20. Percentage of calcium in calcium carbonate is
(a) 40
(b) 30
(c) 48
(d) 36

21. Which has maximum number of molecules?
(a) 1 g of CO₂
(b) 1 g of N₂
(c) 1 g of H₂
(d) 1 g of CH₄

22. What mass of carbon dioxide (CO₂) will contain 3.011 × 10²³ molecules?
(a) 11.0 g
(b) 22.0 g
(c) 4.4 g
(d) 44.0 g

23. The value of Avogadro’s constant is:
(a) 6.0 × 10²⁴
(b) 6.01 × 10²²
(c) 6.022 × 10²³
(d) 6.022 × 10^-23

24. How many times an atom of sulphur is heavier than an atom of carbon?
(a) 32 times
(b) 12 times
(c) 8/3 times
(d) 12/32 times

25. The number of oxygen atoms in 4.4 g of CO₂ is approx.
(a) 6 × 10²²
(b) 6
(c) 12 × 10²³
(d) 1.2 × 10²³

26. Which of the following represents 12 u?
(a) Mass of 1 hydrogen atom
(b) Mass of C-12 atom
(c) Mass of 0-16 atom
(d) 1/12th of mass of C-12 atom

27. Which of the following would weigh the highest?
(a) 0.2 mole of sucrose (C₁₂H₂₂O₁₁)
(b) 2 moles of CO₂
(c) 2 moles of CaCO₃
(d) 10 moles of H₂O

28. The molecule having an atomicity of 4 is:
(a) Sulphate molecule
(b) Ozone molecule
(c) Phosphorus molecule
(d) Methane molecule

29. Energy can neither be created nor destroyed. it is a
(a) Energy recreation
(b) Energy is cannot reform
(c) Law of conservation of energy
(d) Law of conservation

30. In ammonia , nitrogen and hydrogen is in ratio ………… by mass.
(a) 14:5
(b) 14:3
(c) 14:8
(d) 14:2

31. Smallest particle of matter called
(a) Tiny particle
b) Tiny molecule
(c) Molecule
(d) Atom

32. Atomic radius is measured in
(a) Kg
(b) cm
(c) Mm
(d) nm

33. 1nm means how many meters
(a) 1/10⁹ m
(b) 1/10⁸ m
(c) 1/10^-9 m
(d) 1/10^-8 m

34. An international scientific organization which approves names of elements, symbol and unit called
(a) Periodic table
(b) IUPAC nomenclature
(c) Name system
(d) None of the above

35. Symbol of copper
(a) Co
(b) C
(c) Coo
(d) Cu

36. Atomic number means
(a) Number of electron
(b) Number of proton
(c) Number of neutron
(d) None of the above

37. Group of two or more atoms called
(a) Elements
(b) Molecules
(c) Complex
(d) None of the above

38. Formula of ozone
(a) O₂
(b) O₃
(c) OH
(d) H₂

39. The number of atoms constituting a molecule is known as its
(a) Molecular weight
(b) Atomic number
(c) Atomicity
(d) Molecule

40. Charged species is known as
(a) Electric current
(b) Anions
(c) Ions
(d) Current

41. Name of that compound NaNO₃
(a) Sodium nitrogen oxide
(b) Sodium nitroxide
(c) Sodium nitrite
(d) Sodium nitrate

42. Atomic number of calcium
(a) 5
(b) 18
(c) 20
(d) 22

43. 1 mole is
(a) 6.022 x 10²²
(b) 6.022 x 10²³
(c) 6.028 x 10²²
(d) 6.028 x 10²³

44. Valency of carbon
(a) 2
(b) 4
(c) 8
(d) 7

45. The chemical symbol for sodium is
(a) So
(b) Sd
(c) NA
(d) Na

46. The word “mole” was introduced around 1896 by:
(a) Wilhelm Ostwald
(b) John Dalton
(c) Avogadro
(d) Vergilious

47. A change in the physical state can be brought about
(a) only when energy is given to the system
(b) only when energy is taken out from the system
(c) When energy is either given to, or taken out from the system
(d) Without any energy change

48. Which of the following statements is not true about an atom?
(a) Atoms are not able to exist independently.
(b) Atoms are the basic units from which molecules and ions are formed.
(c) Atoms are always neutral in nature.
(d) Atoms aggregate in large numbers to form the matter that we can see, feel or touch.

49. How many moles are present in 560 g of iron?
(a) 1 mole
(b) 10 moles
(c) 100 moles
(d) 0.1 mole

50. Which pairs of elements have gram molecular mass same as gram atomic mass?
(a) Argon, Nitrogen
(b) Fluorine, Magnesium
(c) Phosphorus, Gold
(d) Silicon, Neon

Answer:

1-a	2-a	3-c	4-b	5-c
6-a	7-c	8-a	9-d	10-b
11-b	12-d	13-c	14-d	15-d
16-a	17-c	18-c	19-d	20-a
21-c	22-b	23-c	24-c	25-d
26-d	27-c	28-c	29-c	30-c
31-d	32-d	33-c	34-b	35-d
36-b	37-b	38-b	39-c	40-c
41-d	42-c	43-b	44-b	45-d
46-a	47-b	48-d	49-b	50-d