Answer:
A. Molarity will increase .
Explanation:
Molarity = moles of solute per litre of solution
= moles of solute / volume of solution
If evaporation occurs , volume of solution decreases and moles of solute remains constant . Hence denominator decreases and numerator remains constant .
Hence the molarity increases .
NaHCO3 is the required substance often used in antacid and is used in Soda Acid Fire Extinguisher.