(a) Why are people living in West Bengal prone to black foot disease?
(b) What is blue-baby syndrome ? Explain.

Why do people prefer to live in certain regions and not in others? Explain with example.

In the given region in Japan, fish eating people developed Itai-Itai disease. What was the cause of disease and the phenomenon involved ? Explain

(a) Why are $Z{n}^{2+}$ salts white while $C{u}^{2+}$ salts are blue ? (b) What is meant by 'disproportionation' ? Write the disproportionation reaction of $C{u}^{+}$ in aqueous solution.

Explain the following :
(a) How does the middle ear help in hearing ?
(b) Why does vitamin A deficiency produce night-blindness ?
(c ) What is the role of lacrimal gland ?
(d) How does the iris adjust the size of the pupil ?

(a) Explain why antibiotics are more effective in curing bacterial disease than viral diseases?
(b) List two means of spreading of infectious disease.

(a)What is the significance of meiosis-I?
(b)Why meiosis-II is necessary?Explain.

(a) Why are infrared waves often called heat waves? Explain.
(b) What do you understand by the statement, "Electromagnetic waves transport momentum"?

(a) Why are infra-red waves often called heat waves ? Explain.
(b) What do you understand by the statement, ..Electromagnetic waves transport momentum.. ?

(a) What is corrosion?
(b) Name any two metals which do not corrode easily.
(c) What is the corrosion of iron known as?
(d) Explain why aluminium is a highly reactive metal, still it is used to make utensils for cooking.

In Tamil Nadu, 90 per cent of the people living in rural areas use a ration shop, whereas in West Bengal only 35 percent of rural people do so. Where would people be better off and why?