Class IX Chapter : Atoms and Molecules Date of Taking Test : June 24, 2026 Time: 20 Minutes 1. Which of the following elements are monoatomic elements? (a) Hydrogen, oxygen and Sulphur (b) Helium, neon, and argon (c) Chlorine, bromine and iodine (d) Helium, argon, ozone None 2. Which of the following is the formula for ammonia? (a) NH4 (b) NH4+ (c) NH3 (d) NO2 None 3. Identify which of the formulae is incorrect. (a) CaCO3 (b) CO2 (c) H2O (d) HCl2 None 4. Which of the following is the formula of sodium sulphate? (a) Na2SO4 (b) Na2SO3 (c) Na2S (d) Na2SO5 None 5. Which of the following is not a polyatomic ion? (a) SO4 2- (b) SO3 2- (c) HSO4 -1 (d) SO2 None 6. What is the relative molecular mass of calcium hydroxide? (a) 63 (b) 74 (c) 58 (d) 57 None 7. Which of the following can be treated as an anion? (a) Ammonium (b) Copper (c) Nitrate (d) Iron None 8. Which of the following is the symbol for kalium? (a) Na (b) Ca (c) Fe (d) K None 9. Which of the following is correct? (a) In water, the ratio of hydrogen to oxygen is 1:8 (b) In water, the ration of hydrogen to oxygen is 2:8 (c) In water, the ration of hydrogen to oxygen is 8:16 (d) In water, the ratio of hydrogen to oxygen is 8:1 None 10. Which of the following is not a postulate of Dalton’s atomic theory? (a) The atoms cannot be further divided; they cannot be destroyed nor created in a chemical reaction. (b) In each element, all the atoms are identical in mass and chemical properties (c) The atoms of different elements have the same masses and chemical properties. (d) The atoms combine to create compounds in a ratio of small whole numbers. None 11. Assertion (A): In a chemical reaction, the sum of the masses of reactants = sum of the masses of products. Reason (R): According to the law of conversation of mass, the mass is neither created nor destroyed. (a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true and R is NOT the correct explanation of A (c) A is true but R is false (d) A is false but R is true None 12. Assertion (A); In a pure substance, the elements are present in a definite proportion by mass Reason (R): The elements present in compound, regardless of how they are prepared, the ratio remains the same. (a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true and R is NOT the correct explanation of A (c) A is true but R is false (d) A is false but R is true None 13. Assertion (A): The atoms can be further sub-divided. Reason (R): The atoms of a given element are identical in mass. (a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true and R is NOT the correct explanation of A (c) A is true but R is false (d) A is false but R is true None 14. Assertion (A): The atomic radius is measured in terms of nanometers Reason (R): 1 m is equal to 10 -8 nm (a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true and R is NOT the correct explanation of A (c) A is true but R is false (d) A is false but R is true None 15. Assertion (A): The symbol for mercury is Hg. Reason (R): The symbol of mercury is derived from its Latin name Hydrargyrum. (a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true and R is NOT the correct explanation of A (c) A is true but R is false (d) A is false but R is true None 1 out of 1 Leave a Reply Cancel replyYour email address will not be published. Required fields are marked *Name * Email * Website Comment * Save my name, email, and website in this browser for the next time I comment.