Exothermic is the right kind of reaction.
The answer I believe is c
Explanation
During the day when temperatures are higher, the snow melts and water enters the cracks in the rock. When the temperature drops below 0°C the water in the crack freezes and expands by about 9 per cent. This makes the crack larger.
The answer is A) More than 100 times greater than the electrical force
The two stars should be the same age, so we'd expect the subgiant to be more massive than the main-sequence star.
C. water
answer a has one sodium atom and one chlorine atom
answer b is a chemical reaction
answer d has only one hydrogen atom and one oxygen atom
