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 number of gram-molecules of O2 in 6.023 x 10^24 CO molecules is 1 gram-molecule 10 gram-molecules. 5 gram-molecules. 0.5 gram-molecule. None 2. A sample of pure water, irrespective of source, contains 88.89% oxygen and 11.11% hydrogen by mass. The data supports the Law of multiple proportions None of these Law of constant composition Law of conservation of mass None 3. Phosphorus is : Triatomic Tetra-atomic Diatomic Monatomic None 4. Which of the following is a binary compound? H2SO4 NaH CaCO3 KNO3 None 5. Which has the largest number of molecules? 46 g of C2H5OH 36 g of H2O 54gN2 O5 28 g of CO2 None 6. 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 6.023 x 10^23 2 x 6.023 x 10^23 None 7. An atom is the smallest particle of matter known radioactive emission. smallest particle of a gas smallest indivisible particle of an element that can take part in a chemical change None 8. The element whose gram-atomic mass and gram-molecular mass are the same is hydrogen nitrogen argon oxygen None 9. The formula of a compound is Ca3 (PO4)2. What is the valency of Ca in it? 2 3 4 0 None 10. The mass percentage of hydrogen (H) in water is 1.11 88.88 8.88 11.11 None 11. The accepted unit of atomic mass and molecular mass is g mol-1 kg g amu None 12. The reference standard used for defining atomic mass unit is H C-14 C-12 C-13 None 13. Who suggested that if we go on dividing matter, a stage will come when particles obtained can’t be divided further? Joseph L Proust Democritus and Leucippus Antoine L Lavoisier None of these None 14. 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 1:2 63.5 : 16 63.5 : 8 2:1 None 15. The mass of one Avogadro’s number of N atoms is equal to 14 amu 14 kg 14 g 28 g 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.
