Questions

Both warmth and moisture reduce the density of air and hence its pressure is high.

Cooked food create an enabling environment for bacteria to grow because of their moisture content & of the normal temperature of the food. 

Raw food does not offer suitable conditions for bacteria growth. 

Hence, from the given options raw carrots does not support bacterial growth.

A concentrated solution will contain the most solute molecules per solvent molecules.

Here in the given options,

1)  6/10 = 0.6

2) 20.5/50 = 0.41

3) 30/120 = 0.25

4) 2.6/2 = 1.3

Hence, option D) is most concentrated.