Down there (pls hurryy!!)

D. is the correct answer.

There are many changes that can increase the rate of chemical reaction but the most significant is

Adding a catalyst to the reaction mixture.

The other changes that can increase the rate of chemical reaction are;

Change in temperature (increasing the temperature)

Change of pressure (higher pressure)

pH of the solution (optimum pH)

Change in concentration (Increasing the concentration of the reactants)

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%

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)