Question 1

Who established the two important laws of chemical combination?

Accepted Answer

Antoine L. Lavoisier and Joseph L. Proust established the two important laws of chemical combination, which laid the foundation for modern chemistry.

Question 2

What does the Law of Conservation of Mass state?

Accepted Answer

The Law of Conservation of Mass states that mass can neither be created nor destroyed in a chemical reaction.

Question 3

Who stated the Law of Constant Proportions?

Accepted Answer

Joseph Proust stated the Law of Constant Proportions, which states that in a chemical substance the elements are always present in definite proportions by mass.

Question 4

In water (H2O), the ratio of the mass of hydrogen to the mass of oxygen is always:

Accepted Answer

In water, the ratio of the mass of hydrogen to the mass of oxygen is always 1:8, regardless of the source of water.

Question 5

Who provided the first basic theory about the nature of matter?

Accepted Answer

John Dalton provided the atomic theory of matter which proposed that all matter is made of very tiny particles called atoms.

Atoms and Molecules — CBSE Class 9 Science Important Questions & Revision Notes