Ncert – class 9- science – Chapter 3 – Atoms and Molecules 2 Welcome to your Ncert - class 9- science - Chapter 3 – Atoms and Molecules 2 1. The accepted unit of atomic mass and molecular mass is g mol-1 kg amu g None 2. The mass percentage of hydrogen (H) in water is 8.88 11.11 1.11 88.88 None 3. The formula of a compound is Ca3 (PO4)2. What is the valency of Ca in it? 0 2 3 4 None 4. Who suggested that if we go on dividing matter, a stage will come when particles obtained can’t be divided further? Democritus and Leucippus None of these Antoine L Lavoisier Joseph L Proust None 5. Phosphorus is : Triatomic Monatomic Tetra-atomic Diatomic None 6. Which has the largest number of molecules? 46 g of C2H5OH 28 g of CO2 36 g of H2O 54gN2 O5 None 7. The element whose gram-atomic mass and gram-molecular mass are the same is hydrogen argon oxygen nitrogen None 8. 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 : 8 63.5 : 16 1:2 2:1 None 9. 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 multiple proportions Law of constant composition None of these None 10. The mass of one Avogadro’s number of N atoms is equal to 14 kg 14 amu 28 g 14 g None 11. The number of gram-molecules of O2 in 6.023 x 10^24 CO molecules is 1 gram-molecule 0.5 gram-molecule. 10 gram-molecules. 5 gram-molecules. None 12. An atom is the smallest particle of matter known radioactive emission. smallest indivisible particle of an element that can take part in a chemical change smallest particle of a gas None 13. The number of atoms of hydrogen present In 1 mole of ethyne (C2H2) is 2 x 6.023 x 10^23 8 x 6.023 x 10^23 4 x 6.023 x 10^23 6.023 x 10^23 None 14. Which of the following is a binary compound? CaCO3 NaH KNO3 H2SO4 None 15. The reference standard used for defining atomic mass unit is C-13 C-14 C-12 H 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.
