Give reason
In the same period or subgroup a gradual change in a particular property may be seen.

Give reason : Stretching a rubber band is a physical change.

Give a reason why completion of each period is logical

Give reasons Physical properties of isotopes are different

Why do elements in the same period have different physical and chemical properties? What about elements in the same group?

List the groups, and give reason for placing each material under a particular group.

Given below is an experimental set-up to demonstrate a particular process. Study the same and answer the questions that follow : What would you observe in the experimental set up after an hour? Give a reason to support your answer.

Give reasons for the observation seen during catalytic oxidation of ammonia.

Give three reasons why a frog and a mouse are classified in same phylum.

The value of standard free energy change (DeltaG^(@)) of a redox reaction at a particular temperature may be calculated safely from measurnments of