Class 9 Science MCQ Chapter 3 Atoms and Molecules, Class 9 Science MCQ Question Answer, Class 9 Science Multiple Choice Question Answer to each chapter is provided in the list of SCERT Science Class 9 Objective Types Question Answer so that you can easily browse through different chapters and select needs one. Class 9 Science MCQ Chapter 3 Atoms and Molecules Question Answer can be of great value to excel in the examination.
SCERT Class 9 Science MCQ Chapter 3 Atoms and Molecules
SCERT Class 9 Science MCQ Chapter 3 Atoms and Molecules Notes covers all the exercise questions in SCERT Science Textbooks. The NCERT Class 9 Science MCQ Chapter 3 Atoms and Molecules provided here ensures a smooth and easy understanding of all the concepts. Understand the concepts behind every chapter and score well in the board exams.
Atoms and Molecules
Chapter – 3
Multiple Choice Questions & Answers
1. If 9g of water is decomposed, it is always obtained –
(a) 2 g of hydrogen and 7 g of oxygen
(b) 1 g of hydrogen and 8 g of oxygen
(c) 3g of hydrogen and 6 g of oxygen
(d) 4 g of hydrogen and 5 g of oxygen
Ans. (b) 1 g of hydrogen and 8 g of oxygen.
2. The value of 1 metre is –
(a) 10⁹ nm
(b) 10⁸ nm
(c) 10¹⁰ nm
(d) 10¹¹ nm
Ans.(a) 10⁹ nm.
3. Relative size of a ant is –
(a) 10⁻³ m.
(b) 10⁻⁴ m.
(c) 10⁻³ m.
(d) 10⁻² m.
Ans. (d) 10⁻² m.
4. Symbol for Hydrogen as proposed by Dalton was –
Ans. (c)
5. The symbol of the element ‘cobalt’ is
(a) CO
(b) Co
(c) CB
(d) Cb
Ans. (b) Co.
6. If 7g of carbon monoxide (CO) is decomposed, it is always obtained –
(a) 3g of carbon and 4g of oxygen.
(b) 2g of carbon and 5g of oxygen.
(c) 4g of carbon and 3g of oxygen.
(d) 5g of carbon and 2g of oxygen.
Ans.(a) 3g of carbon and 4g of oxygen.
7. which of the following statement is correct?
(a) as the average mass of the atom as compared to ¹/₁₂ th the mass of one carbon – 12 atom.
(b) as the average mass of the atom,as compared to ¹/₁₂ th the mass of one carbon – 13 atom.
(c) as the average mass of the atom,as compared to ¹/₁₁ th the mass of one carbon-13 atom.
(d) as the average mass of the atom, as compared to 1⅒ th the mass of one carbon-12 atom.
Ans.(a) as the average mass of the atom as compared to ¹/₁₂ atom. th the mass of one carbon – 12 atom.
8. Which of the following is atomic mass unit of chlorine?
(a) 32.5
(b) 33.5
(c) 34.5
(d) 35.5
Ans. (d) 35.5.
9. Which of the following is monatomic element?
(a) Nitrogen
(b) Hydrogen
(c) Helium
(d) oxygen
Ans. (c) Helium.
10. Which of the following is diatomic element?
(a) Argon
(b) Chlorine
(c) Phosphorus
(d) Sulphur
Ans. (b) Chlorine.
11. Which of the following is Tetra-atomic element?
(a) Phosphorus
(b) Chlorine
(c) Nitrogen
(d) Oxygen
Ans. (a) Phosphorus.
12. Which of the following is tetra-atomic molecules?
(a) Oxygen
(b) Ozone
(c) Hydrogen
(d) Nitrogen
Ans. (b) Ozone.
13. What is the ratio of mass between carbon and oxygen in carbon dioxide?
(a) 3:8
(b) 5:6
(c) 2:9
(d) 7:4
Ans.(a) 3:8
14. What is the Symbol of polyatomic ions of Sulphate?
(a) So₂²–
(b) So₃²–
(c) So₄²–
(d) So₄²+
Ans. (c) So₄²-
15. What is the symbol of oxide ion?
(a) 0²⁺
(b) 0³⁺
(c) O⁻
(d) 0²⁻
Ans. (d) 0²⁻
Very Short Answer Type Questions
1. State law of conservation of mass.
Ans. Mass can neither be created nor destroyed in a chemical reaction.
2. State the law of definite proportions.
Ans. In a chemical substance the elements are always present in definite proportions by mass.
3. What is the definition of atom, which is provide by Dalton?
Ans. All matter is made of very tiny particles called atoms.
4. What is the full form of IUPAC?
Ans. International union of pure and Applied chemistry.
5. Which word that copper was taken?
Ans. Cyprus.
6. What do you mean by one atomic mass unit?
Ans. A mass unit equal to exactly one-twelfth (1/12th) the mass of one atom of carbon – 12 is called one atomic mass unit.
7. What do you mean by the relative atomic mass?
Ans. The relative atomic masses of all elements have been found with respect to an atom carbon-12.
8. What is an ion?
Ans. Compounds composed of matals and non-metals contain charged species. The charged species are known as ions.
9. What is cation?
Ans. The positive charged ion is called cation.
10. What is anion?
Ans. A negatively charged ion is called anion.
11. What are cation and anion of NaCl?
Ans. Cation is Nat and anion is, C1–.
12. What is polyatomic ion?
Ans. A group of atoms carrying a charge is known as a polyatomic ion.
13. Write the polyatomic iors which symbol is Co₃²-?
Ans. Carbonate.
14. Write the formula of sodium Nitrate.
Ans. NaNo₃.
15. Write down of compounds represented by the following formulae of
(a) (NH₄)₂So₄
(ii) CaCo₃
Ans. (i) Ammonium Sulphate.
(ii) Calcium Carbonate.
16. Calculate the relative molecular mass of
(i) water
(ii) HNO₃
Ans. (i) two atoms of hydrogen and of oxygen is = 2 x 1+1 x 16 = 18 u
(ii) the atomic mass of H+ the atomic mass of N +3× atomic mass of
O = 1+14+3 x 16
= 63 u
17. What do you means by 1 mole?
Ans. A substance is equal to its relative atomic or molecular mass in grams is called one mole.
18. What is called Avogadro constant?
Ans. The number of particles present in 1 mole of any substance is fixed, with a value of 6.022 x 10²³. This number is called the avogadro constant.
19. What do you mean by 1u hydrogen?
Ans. 1 atom of hydrogen.
20. What do you mean by 1g hydrogen?
Ans. 6.022 × 10²³ atoms of hydrogen.
21. Give the names of the elements present in the following compounds.
(a) Quick lime
(b) Baking powder
Ans. (a) Calcium and oxygen.
(b) Sodium, hudrogen, carbon and oxygen.
22. What is the mass of 1 mole nitrogen atoms?
Ans. 14g.
23. Convert into mole of 12 g of oxygen gas.
Ans. 32g is = mole
1g is = 1/32 mole
12g is = 1/32× 12 mole
= 0.375 mole.
24. What is the mass of 0.5 mole of water molecules?
Ans. 1 mole is = 18g
0.5 mole is = 18g×.5
= 9g.
25. What is called molar mass?
Ans. Mass of 1 mole of a substance is called molar mass.
