MCQ Laws of Chemical Combination Chapter 3 Class 9 Science

MCQ’s For All Chapters – Science Class 9th

1. There will be total 24 MCQ in this test.
2. Please keep a pen and paper ready for rough work but keep your books away.
3. The test will consist of only objective type multiple choice questions requiring students to mouse-click their correct choice of the options against the related question number.
4. No negative marking for incorrect choice.
5. Please click on “Finish the Test” when you want to exit.
6. All the best – Happy Studying

1. A student heats 25g of reactant 'A' with 50g of reactant 'B'. He obtains 50g of product 'C' and recovers 25 g of unreacted 'B'. Which of the following law is confirmed in the following reaction?

Law of constant proportion

Law of conservation of mass

Law of conservation of mass and Law of constant proportion

Law of multiple proportion

Your comments:

Question 1 of 24

2. Law of conservation of mass can be derived from which postulate of Dalton's atomic theory?

Atoms of a given element have same mass and chemical properties.

Matter is made of tiny particles.

Atom can neither be created nor destroyed.

The relative number and kind of atoms are constant in a given compound.

Your comments:

Question 2 of 24

3. 5 grams of compound A reacts with 10 grams of compound B to produce a new compound C. What should be the mass of C according to law of conservation of mass?

15 g

5 g

50 g

10 g

Your comments:

Question 3 of 24

4. According to Law of conservation of mass, mass of reactants wil be equal to the mass of:

Catalysts

Products

Apparatus used for reaction

Gases evolved

Your comments:

Question 4 of 24

5. The reaction used in the experiment to verify the law of conservation of masses is included in which of the following categories?

Precipitation reaction

Double displacement reaction

Neutralization reaction

Both A and B

Your comments:

Question 5 of 24

6. The atomic masses and chemical properties of Sulphur and Phosphorus are different. This can be explained on the basis of:

Law of conservation of mass

Laws of Chemical combination

Law of constant proportions

Dalton's Atomic theory

Your comments:

Question 6 of 24

7. When CaCO₃ is heated, it forms CaO and CO₂. Which of these statements best describes the mass of the products if 100 g of CaCO₃ is heated?

The difference in the products' masses is equal to the mass of the CaCO₃.

The mass of each product is equal to the mass of the CaCO₃.

The sum of the products' masses equals the mass of the CaCO₃.

The sum of the products' masses is less than the mass of the CaCO₃.

Your comments:

Question 7 of 24

8. According to the law of conservation of mass, 3 g of carbon burnt in 8 g of oxygen forms 11 g of carbon dioxide. Now, what will be the mass of carbon dioxide produced when 3 g of carbon is burnt in 50 g of oxgyen?

53 g

47 g

45 g

50 g

Your comments:

Question 8 of 24

9. Which of the following statements is true about the law of conservation of mass?

In a chemical reaction, efforts should be made to preserve rare elements without changing them.

In a chemical reaction, the final mass of the products is always greater than the starting mass of the reactants.

In a chemical reaction, matter is not created or destroyed, but is conserved.

Matter can be created and destroyed but does not change forms.

Your comments:

Question 9 of 24

10. Which of the following statements is true about ‘Law of conservation of mass"?

If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.

The elements are always present in a constant proportion in a chemical substance.

The rate of reaction is directly proportional to the active mass of the reactants.

Substances involved in a chemical reaction can change their states but the total mass of the product will be equal to that of the product.

Your comments:

Question 10 of 24

11. Who gave the Law of constant proportions?

Cavendish

Proust

Dalton

Lavoisier

Your comments:

Question 11 of 24

12. Which of the following statement is not in accordance with Dalton's atomic theory?

All matter is made up of very tiny particles called atoms.

Atoms can be divided into proton, neutron and electrons.

Atoms of given element are identical in mass and chemical properties.

Atoms combine in the ratio of small whole numbers to form compounds.

Your comments:

Question 12 of 24

13. Which of the following is the major drawback of Dalton's atomic theory?

Atoms of an element have exactly the same mass.

Atoms are indivisible.

Atoms of different elements have different masses.

All of the above

Your comments:

Question 13 of 24

14. Which of the following is correct for the 'Law of Conservation of Mass'?

Mass can neither be created nor destroyed.

The rate of reaction is directly proportional to the active mass of the reactants.

Mass can either be created or destroyed in a chemical reaction.

The elements are always present in a constant proportion in a chemical substance.

Your comments:

Question 14 of 24

15. The balancing of chemical equation is based upon:

Law of conservation of mass

Law of multiple proportions

Law of definite proportion

Law of combining volumes

Your comments:

Question 15 of 24

16. Which of the following is not a postulate of Dalton's atomic theory?

The number of atoms in a given compound is fixed.

Atoms of the same elements cannot combine in more than one ratio to form more than one compound.

Atoms can neither be created nor destroyed.

Atoms cannot be divided.

Your comments:

Question 16 of 24

17. Which type of reaction is being used in the experiment of verifying the law of conservation of mass?

Displacement reaction

Precipitation reaction

Double decomposition reaction

Decomposition reaction

Your comments:

Question 17 of 24

18. 9 grams of water decompose to give:

4g oxygen and 16g hydrogen

2g hydrogen and 1g oxygen

8g oxygen and 1g hydrogen

1g hydrogen and 8g oxygen

Your comments:

Question 18 of 24

19. Who stated the Law of conservation of mass?

Thomson

Lavoisier

Dalton

Cavendish

Your comments:

Question 19 of 24

20. If all the reactants in a chemical reaction are completely used, which of the following statements accurately describes the relationship between the reactants and the products?

The reactants must contain more complex molecules than the products do.

The products must have different physical state than the reactants.

The total mass of the reactants must equal the total mass of the products.

The density of the reactants must equal the density of the products.

Your comments:

Question 20 of 24

21. Assertion : The valency of aluminium is 3 and oxygen is 2.
Reason : The chemical formula of aluminium oxide is Al3O2.

a.) Both Assertion and Reason are correct, and reason is the correct explanation for assertion.

b.) Both Assertion and Reason are correct, and Reason is not the correct explanation for Assertion.

c.) Assertion is true but Reason is false.

d.) Assertion is false but Reason is true

Question 21 of 24

22. Assertion : A molecule is the smallest particle of an element or a compound which is capable of free existence.
Reason : The number of atoms present in one molecule of the substance is called its atomicity.

a.) Both Assertion and Reason are correct, and reason is the correct explanation for assertion.

b.) Both Assertion and Reason are correct, and Reason is not the correct explanation for Assertion.

c.) Assertion is true but Reason is false.

d.) Assertion is false but Reason is true

Question 22 of 24

23. Assertion: Water molecules always contain hydrogen and oxygen in the ratio 1:8.
Reason: Water obeys law of constant proportions irrespective of source and method of preparation.

a.) Both Assertion and Reason are correct, and reason is the correct explanation for assertion.

b.) Both Assertion and Reason are correct, and Reason is not the correct explanation for Assertion.

c.) Assertion is true but Reason is false.

d.) Assertion is false but Reason is true

Question 23 of 24

24. Assertion : Ions are always positively charged.
Reason : Ions are formed by losing or gaining electrons.

a.) Both Assertion and Reason are correct, and reason is the correct explanation for assertion.

b.) Both Assertion and Reason are correct, and Reason is not the correct explanation for Assertion.

c.) Assertion is true but Reason is false.

d.) Assertion is false but Reason is true

Question 24 of 24