Atoms and Molecules MCQ Question Answers Class 9 Science Chapter 3


CBSE Class 9 Science Chapter 3 “Atoms and Molecules Multiple Choice Question Answers”


Atoms and Molecules MCQ – Here is a compilation of Free MCQs of Class 9 Science Book Chapter 3 Atoms and Molecules with Answers.  Students can practice free MCQs as have been added by CBSE in the new Exam pattern. At the end of Multiple- Choice Questions, the answer key also has been provided for your reference. Also, Take Free Online MCQ Test for Class 9.


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Q.1. Laws which explain the formation of many oxides by nitrogen is

(a) Law of conservation of mass

(b) Law of multiple proportions

(c) Law of definite proportions

(d) Avogadro’s law



Q.2. Which of the following is not equal in mass to the 116th part of an oxygen atom?

(a) 14th of helium atom

(b) 112th of carbon atom

(c) 128th of nitrogen atom

(d) None of these



Q.3. Name the salts which contain the same number of ions per molecule as magnesium nitride.

(i) Aluminium phosphate

(ii) Potassium sulphite

(iii) Barium phosphate

(iv) Ferric chromate


(a) i, iii, iv

(b) ii, iv

(c) i, iii

(d) iii, iv 



Q.4. 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



Q.5. What would be the gram molecular mass of solid sulphur?

(a) 256 g

(b)  128 g

(c) 64 g

(d) 32 g



Q.6. Identify the number of ions in 1 mole of ferric sulphate.

(a) 3 x 1024

(b) 9 x 1024

(c) 1.02 x 1025

(d) 1.2 x 1024



Q.7. How many moles are present in 560 g of iron?

(a) 1 mole

(b) 10 moles

(c) 100 moles

(d) 0.1 mole



Q.8. The central atom does not acquire stable octet configuration in which of the following molecules

(a) Carbon dioxide

(b) Methane

(c) Boron trichloride 

(d) Ammonia



Q.9. In which of the following compounds, formula unit mass is considered instead of molecular mass? 

(a) Carbon tetrachloride

(b) Phosphorus pentoxide

(c) Barium bromide

(d) Sulphur hexafluoride


Q.10. From which oxyacid two acidic radicals can be derived.

(a) Phosphoric acid

(b) Sulphurous acid

(c) Nitric acid

(d) Chlorous acid



Q.11. A metal can form two Sulphides. In one Sulphide, the metal and Sulphur atoms are in the ratio of 2:1. In the other, the metal and Sulphur atoms are in the ratio 2:3. The metal which complies with the above compounds is.

(a) Gold 

(b) Copper

(c) Iron

(d) Lead



Q.12. According to the law of definite proportions, ________.

(a) matter remains constant

(b) matter can neither be created nor destroyed matter remains constant

(c) a chemical compound is always made up of the same element combined together in the same fixed proportion matter remains constant

(d) All of these



Q.13. Three-fourth mass of a substance contains the same number of molecules as in a certain mass of Sulphur dioxide. Identify the substance among the following.

(a) Methane

(b) Ozone 

(c) Sulphur trioxide

(d) Oxygen



Q.14. When alpha-particles are sent through a thin metal foil, most of them go straight through the foil because, _______.

(a) alpha-particles are much smaller than electrons.

(b) alpha-particles are positively charged

(c) most part of the atom is empty space

(d) alpha-particles move with a low velocity



Q.15. Which among the following formulae is wrong?

(a) MClO3

(b) M(ClO3)2

(c) M(ClO3) 3

(d) M2ClO3



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