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