ICSE ICSE Class 8 - CISCE Question Bank Solutions

Fill in the blank.

There is no change in the _____________of the substance during a physical change.

Fill in the blank.

The reaction in which energy is evolved is called

Given reason:

Freezing of water to ice and evaporation of water are physical changes.

Given reason:

Burning of paper is a chemical change.

Given reason:

Cutting of a cloth piece is a physical change, though it cannot be reversed.

Give four difference between physical and chemical changes.

State its one drawback of Rutherford’s atomic model.

Define the term Mass number.

Define the term Nucleons.

Define the term Valence shell.

State the following pertaining to the physical properties of hydrogen: Colour & odour

State the following pertaining to the physical properties of hydrogen: Solubility in water

State the following pertaining to the physical properties of hydrogen: Effect on moist blue litmus paper.

With reference to the uses of hydrogen, give reason for the following:

Hydrogen is not used in air balloons

With reference to the uses of hydrogen, give reason for the following:

A mixture of hydrogen & oxygen on burning, find application in welding & cutting metals.

With reference to the uses of hydrogen, give reason for the following:

Reaction of hydrogen with nitrogen under specific conditions finds industrial utility.

Explain how the modern atomic theory contradicted Dalton’s atomic theory.

With reference to the discovery of the structure of an atom, explain in brief – William Crookes experiment for the discovery of cathode rays, followed by – J.J. Thomsons experiment pertaining to the constituents of the cathode rays. State which sub-atomic particle was discovered from his experiment.

Explain in brief – Goldstein’s experiment which led to the discovery of the proton.

Draw a neat labelled diagram representing an atom. Name the three sub-atomic particles in the atom and represent them symbolically showing the mass and charge of each. State where the sub-atomic particles are present in the atom.