Can you think of a reason why the metals sodium is usually stored under oil? What might happed if it is exposed to air, especially on a damp day?

a. A comb run through one's dry hair attracts small bits of paper. Why? What happens if the hair is wet or if it is a rainy day? (Remember, a paper doesn't conduct electricity.) b. Ordinary rubber is an insulator. But special rubber tyres of aircraft are made slightly conducting. Why is this necessary? c. Vehicles carrying inflammable materials usually have metallic ropes touching the ground during motion. Why? d. A bird perches on a bare high power line, and nothing happens to the bird. A man standing on the ground touches the same line and gets a fatal shock. Why?

What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?

A freshly cut piece of sodium when exposed to air for some time looses its lustre in the freshly cut portion. a) What may be the reason for this?. b) Write any two chemical equations to substantiate your answer.

A student is doing an experiment in the laboratory using sodium. Suddenly, a piece of sodium falls into liquid ammonia. (a) What changes can you observe in liquid ammonia? (b) What is the reason for the change? (c) If the solution is kept for a long time it is changed into bronze colour. Why?

Nicotiana sylvestris flowers only during long days and N.tobacum flowers only during short days. If raised in the laboratory under different photoperiods. they can be induced to flower at the same time and can be cross fenjlized to produce self-fertile offspring. What is the best reason for considering N. sylvestfis and N. tobocum to be separate species?

Iron is a metal which corrodes fast. What are the factors that favour the corrosion of iron? In coastal regions, copper nails are preferred to iron nails. What could be the reason? Can you suggest some measures to prevent the corrosion of iron?

The size of air bubbles rising from the bottom of an aquarium increases. Can you explain the reason? What do you observe?