Q.1 Non-biodegradable pollutants are created by

1. nature

2. excessive use of resources

3. humans

4. natural disasters

Q. 8 Which of the following material takes the longest time for biodegradation?

1. Cotton

2. Paper

3. Bone

4. Jute

Q.17 Which one of the following impurities is easiest to remove from waste
water?

1. Bacteria

2. Colloids

3. Dissolved solids

4. Suspended solids