In areas where freezing and thawing occur frequently, rocks weather rapidly because of the of freezing water. a. evaporation c. leaching b. expansion d. oxidation

b. expansion

Explanation:

The rapid freezing and thawing will be responsible for mechanical weathering of the rocks by the process of frost wedging. In this condition the temperature outside the rock causes the disintegration of the rock.

In cold temperature the water inside the rock get freezed and when the temperature outside the rock becomes normal the water attains it's liquid form this is called as thawing.

On freezing the surface area of the ice expands inside the rock which leads to the disintegration of the rock structure from inside. Thus results in weathering.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%