Discuss why wearing more layers of clothing during winter* keeps us warmer than wearing just one thick piece of clothing.

Why two thin blankets put together are warmer than one blanket of double the thickness ?

Why should we wear cotton clothes in summer?

Write the chemical formula of washing soda. How is it obtained from baking soda ? Name one use of washing soda, other than washing clothes.

Properties of the elements are given below. Where would you locate the following elements in the periodic table? a] A soft metal stored under kerosene. b] An element with variable (more than one) valency stored under water. c] An element which is tetravalent and forms the basis of organic chemistry d] An element which is an inert gas with atomic number 2. e] An element whose thin oxide layer is used to make other elements corrosion resistant by the process of "anodising".

We use colours dissolved in water during Holi and clothes gets spoiled. Many colours used to celebrate Holi are oxidized metals or industrial dyes mixed with engine oil. Doctors say these are harmful colours which should be banned for usage. Manufactures mix dyes with colours, and sell them for their profits. Holi lovers can make their Holi colourful by using natural colours available in the market.Natural colours start fading when they come in contact with sun rays. (i) Why doctors say that synthetic colours are harmful? (ii) What are natural colours? (iii) As a student what initiative you will take to motivate your classmates to use natural colours in Holi? Give any suggestions.