The answer is A because I did this before
Answer: Calcium Sulphate Hemihydrate
The compound of calcium which is used for plastering of fractured bones is Plaster of Paris. It is also called as Calcium Sulphate Hemihydrate.
Answer: When the reaction reaches equilibrium, the cell potential will be 0.00 V
Explanation:
Equilibrium state is the state when reactants and products are present but the concentrations does not change with time.
The equilibrium is dynamic in nature and the reactions are continuous in nature. Rate of forward reaction is equal to the rate of backward reaction.
The standard emf of a cell is related to Gibbs free energy by following relation:

The Gibbs free energy is related to equilibrium constant by following relation:

For equilibrium 
Thus 

Thus When the reaction reaches equilibrium, the cell potential will be 0.00 V
The volume of the gas at STP = 35.01 L
<h3>Further explanation</h3>
Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure).
In general, the gas equation can be written

where
P = pressure, atm
V = volume, liter
n = number of moles
R = gas constant = 0.08206 L.atm / mol K
T = temperature, Kelvin
V=17.4 L
T = 23 + 273 = 296 K
P = 2.18 atm

The volume of the gas occupy at STP :
