| Class | 9th |
| Subject | Science |
| Chapter 3 | Atoms and Molecules |
| Questions Type | MCQs |
| pdf File Download | Available |
Class 9 Science Atoms and Molecules MCQ
1. A sample of NH3 molecule irrespective of source contains 82.35% Nitrogen and 17.65% of Hydrogen by mass. This data supports:
(A) Law of Conservation of Mass
(B) Law of Multiple proportions
(C) Law of constant proportions
(D) Avogadro’s Law
Correct answer: (C)
2. In water, the proportion of oxygen and hydrogen by mass is:
(A) 1 : 4 (B) 1 : 8
(C) 4 : 1 (D) 8 : 1
Correct answer: (D)
3. Calcium carbonate decomposes on heating, to form calcium oxide and carbon dioxide. When 10g of calcium carbonate is decomposed completely, then 5.6g of calcium oxide is formed. Calculate the mass of carbon dioxide formed.
(A) 4.4 g
(B) 5.6 g
(C) 4.1 g
(D) 10 g
Correct answer: (A)
4. The mass ratio of carbon and oxygen in all carbon-dioxide samples is 3 : 8. This is in agreement with the law of:
(A) Conservation of mass
(B) Multiple proportions
(C) Constant proportions
(D) Gaseous volumes
Correct answer: (C)
5. Which among the following is not a postulate of Dalton’s atomic theory?
(A) Atoms can-not be created or destroyed
(B) Atoms of different elements have different sizes, masses and chemical properties
(C) Atoms of same elements can combine in only one ratio to produce more than any one compound
(D) Atoms are very tiny particles which can-not be further divided.
Correct answer: (C)
6. Which among the following statement/s is/are correct?
1. The ratio of the mass of hydrogen to the mass of oxygen is always 8:1 in a compound such as water.
2. If 9g of water is decomposed, 1g of
hydrogen and 8g of oxygen are always obtained.
3. Nitrogen and hydrogen are always present in the ratio 3:14 by mass in ammonia.
4. Many compounds are composed of two or more elements and each such compound has the same elements in the same proportions.
(A) 2 and 4
(B) 1, 2 and 3
(C) 1 and 3
(D) 3 only
Correct answer: (A)
7. 9 Grams of water decompose to give:
(A) 4g oxygen and 16g hydrogen
(B) 2g hydrogen and 1g oxygen
(C) 8g oxygen and 1g hydrogen
(D) None
Correct answer: (C)
8. Who coined the term ‘Parmanu’ for the smallest indivisible particles?
(A) Leucippus
(B) L. Lavoisier
(C) Kanad
(D) None of them
Correct answer: (C)
9. The law of conservation of mass was given by:
(A) Dalton
(B) Proust
(C) Lavoisier
(D) Berzelius
Correct answer: (C)
10. Which of the following is Latin name for gold?
(A) Ferrum
(B) Argentum
(C) Natrium
(D) Aurum
Correct answer: (D)
11. What does 1 amu or 1 u mean?
(A) Mass of C-12 atom
(B) 1/12th mass of C-12 atoms
(C) Mass of He-4 atom
(D) Mass of Hydrogen molecule
Correct answer: (B)
12. Which of the following represents the chemical symbol for nitrogen?
(A) Ni
(B) Na
(C) N2
(D) N
Correct answer: (D)
13. Which of the following is the chemical symbol used for cadmium?
(A) Cd
(B) Cu
(C) Cs
(D) Ca
Correct answer: (A)
14. One nm is equal to:
(A) 10–9 mm
(B) 10–7 cm
(C) 10–9 cm
(D) 10–6 m
Correct answer: (B)
15. The scientist who proposed the first letter (or first letter and another letter) of the Latin or English name of an element as its symbol, was :
(A) Dalton
(B) Proust
(C) Lavoisier
(D) Berzelius
Correct answer: (D)
16. The chemical symbol for sodium is
(A) So
(B) Sd
(C) NA
(D) Na
Correct answer: (D)
17. Atomic radius is measured in ………..
(A) Kg
(B) cm
(C) Mm
(D) nm
Correct answer: (D)
18. Choose incorrect option
(A) AL is the symbol of aluminium
(B) Ag is the symbol of silver
(C) Au is the symbol of gold
(D) All of the above
Correct answer: (A)
19. Symbol of copper
(A) Co
(B) C
(C) Coo
(D) Cu
Correct answer: (D)
20. The subatomic particle called electron was discovered by:
(A) J.J. Thomson
(B) Neils Bohr
(C) James Chadwick
(D) E. Goldstein
Correct answer: (A)
21. The first model of an atom was given by:
(A) Neils Bohr
(B) Ernest Rutherford
(C) J.J. Thomson
(D) Eugen Goldstein
Correct answer: (C)
22. Cathode rays are:
(A) Negatively charged particles
(B) Positively charged particles
(C) Neutral particles
(D) None of these
Correct answer: (A)
23. Who discovered proton?
(A) Goldstein
(B) Rutherford
(C) Mendeleev
(D) Thomson
Correct answer: (A)
24. Which of the following models are not the same as Thomson Model of Atom?
(A) plum pudding model
(B) watermelon model
(C) raisin pudding model
(D) nuclear model
Correct answer: (D)
25. What is the absolute charge of a proton?
(A) + 1.602176 × 10–27
(B) –1.602176 × 10–19
(C) +1.602176 × 10–19
(D) – 1.602176 × 10–27
Correct answer: (C)
26. An alpha particle is also known as:
(A) subatomic particle
(B) an unionised helium atom
(C) a neutral particle
(D) a doubly-charged helium ion
Correct answer: (D)
27. The charge on an electron is equal to:
(A) 1.6 × 10–19 C of –ve charge
(B) 2.6 × 10–19 C of –ve charge
(C) 1.6 × 10–22 C of –ve charge
(D) 1.6 × 10–23 C of –ve charge
Correct answer: (A)
28. Rutherford’s alpha particle scattering experiment led to the discovery of:
(A) Nucleus
(B) Electrons
(C) Protons
(D) Neutrons
Correct answer: (A)
29. Goldstein’s experiments which involved passing high voltage electricity through gases at very low pressure resulted in the discovery of:
(A) electron
(B) proton
(C) nucleus
(D) neutron
Correct answer: (B)
30. Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronological order
(i) Rutherford’s atomic model
(ii) Thomson’s atomic model
(iii) Bohr’s atomic model
(A) (i), (ii) and (iii)
(B) (ii), (iii) and i)
(C) (ii), (i) and (iii)
(D) (iii), (ii) and (i)
Correct answer: (C)
31. The nucleons are
(A) Protons and electrons
(B) Neutrons and electrons
(C) Protons and neutrons
(D) None of these
Correct answer: (C)
32. Which of the following statements about Rutherford’s model of atom are correct?
(i) Considered the nucleus as positively charged.
(ii) Established that the α-particles are four times as heavy as a hydrogen atom.
(iii) Can be compared to solar system.
(iv) Was in agreement with Thomson’s model.
(A) (i) and (iii)
(B) (ii) and (iii)
(C) (i) and (iv)
(D) Only (i)
Correct answer: (A)
33. Which scientist gave the concept of fixed energy levels around the nucleus?
(A) Ernest Rutherford
(B) Neils Bohr
(C) J.J. Thomson
(D) None of these
Correct answer: (B)
34. What prevents an atom from being collapsed?
(A) The nuclear forces
(B) Movement of electrons in discrete energy levels
(C) The electron-electron repulsions
(D) All of these
Correct answer: (B)
35. Which of the following is the correct electronic configuration of sodium?
(A) 2, 8, 1
(B) 8, 2, 1
(C) 2, 1, 8
(D) 2, 8, 2
Correct answer: (A)
36. Which of the following represents the correct electronic distribution of magnesium?
(A) 2, 8
(B) 2, 8, 1
(C) 2, 8, 2
(D) 2, 8, 3
Correct answer: (C)
37. The correct electronic configuration of chlorine is:
(A) 2, 8
(B) 2, 8, 4
(C) 2, 8, 8
(D) 2, 8, 7
Correct answer: (D)
38. Number of electrons present in the last shell of calcium is:
(A) 6
(B) 2
(C) 8
(D) 5
Correct answer: (B)
39. How many numbers of electrons can be accommodated in ‘N’ shell:
(A) 18
(B) 16
(C) 32
(D) 2
Correct answer: (C)
40. How many electrons are there in the L-shell of Boron?
(A) 3
(B) 2
(C) 1
(D) 4
Correct answer: (A)
41. How many electrons can the first energy level hold?
(A) 1
(B) 2
(C) 8
(D) 0
Correct answer: (B)
42. What is the electronic configuration of Lithium?
(A) 2.8.8
(B) 2.2.2
(C) 2.8.5
(D) 2.1
Correct answer: (D)
| Chapter -1 Matter in Our Surroundings |
| Chapter – 2 Is Matter Around Us Pure? |
| Chapter -3 Atoms and Molecules |
| Chapter -4 Structure of the Atom |
| Chapter -5 The Fundamental Unit of Life |
| Chapter -6 Tissues |
| Chapter -7 Motion |
| Chapter -8 Force and Laws of Motion |
| Chapter -9 Gravitation |
| Chapter -10 Work and Energy |
| Chapter -11 Sound |
| Chapter -12 Improvement of Food Resources |