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