The most abundant elements is:
1). Silicon
2). Calcium
3). ?Nitrogen
4). Oxygen
2. The name of plastic polymer from which combs, toys, bowls etc., can be made, is
3. Which halide is used in making sensitive emulsion on photograhic film?
4. The material known in commerce as Terylene is a
5. The process of covering water pipes made of Iron with Zinc layer to prevent corrosion is called :
6. Magnesium (Mg) + Oxygen $(O_{2})$ = ?
8. Which of the following is a renewable source of energy ?
9. Which one of the following is extensively used for sterilizing water ?