Ncert – class 9- science – Chapter 3 – Atoms and Molecules 2 Welcome to your Ncert - class 9- science - Chapter 3 – Atoms and Molecules 2 1. An atom is the smallest particle of a gas smallest particle of matter known smallest indivisible particle of an element that can take part in a chemical change radioactive emission. None 2. The mass of one Avogadro’s number of N atoms is equal to 14 kg 14 g 28 g 14 amu None 3. The number of gram-molecules of O2 in 6.023 x 10^24 CO molecules is 5 gram-molecules. 10 gram-molecules. 1 gram-molecule 0.5 gram-molecule. None 4. The number of atoms of hydrogen present In 1 mole of ethyne (C2H2) is 8 x 6.023 x 10^23 4 x 6.023 x 10^23 2 x 6.023 x 10^23 6.023 x 10^23 None 5. Who suggested that if we go on dividing matter, a stage will come when particles obtained can’t be divided further? Antoine L Lavoisier None of these Joseph L Proust Democritus and Leucippus None 6. The formula of a compound is Ca3 (PO4)2. What is the valency of Ca in it? 4 0 2 3 None 7. The accepted unit of atomic mass and molecular mass is g kg g mol-1 amu None 8. Which of the following is a binary compound? NaH KNO3 CaCO3 H2SO4 None 9. Which has the largest number of molecules? 36 g of H2O 28 g of CO2 54gN2 O5 46 g of C2H5OH None 10. A sample of pure water, irrespective of source, contains 88.89% oxygen and 11.11% hydrogen by mass. The data supports the Law of conservation of mass Law of constant composition None of these Law of multiple proportions None 11. The reference standard used for defining atomic mass unit is C-12 H C-14 C-13 None 12. The element whose gram-atomic mass and gram-molecular mass are the same is argon hydrogen nitrogen oxygen None 13. Phosphorus is : Monatomic Tetra-atomic Triatomic Diatomic None 14. The mass percentage of hydrogen (H) in water is 1.11 8.88 88.88 11.11 None 15. Copper reacts with oxygen to form two oxides, Cu2O and CuO. The ratio between the masses of copper which react with a fixed mass of oxygen is 63.5 : 16 63.5 : 8 2:1 1:2 None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to commentEnter your email address to commentEnter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
