Which of the following is the main nitrogenous waste in humans?

1. 1. Ammonia
   2. Urea
   3. Uric Acid
   4. Ammonium Nitrate

Permanent hardness of water is caused due to presence of dissolved

1. 1. Calcium hydrogen carbonates
   2. Magnesium hydrogen carbonates
   3. Both A and B
   4. Sulphate and chlorides of calcium or magnesium

A Hexadecimal number is a number to the base

1. 1. 8
   2. 20
   3. 16
   4. 2

How Many bones are there in the average person’s body?

1. 1. 36
   2. 206
   3. 113
   4. It varies by the individual

White blood cells (WBCs) fight infections from

1. 1. Bacteria
   2. Viruses
   3. Fungi
   4. All of these