Answer:
Exothermic reaction for the HCl, endothermic reaction for the water

Explanation:
Heat was lost by HCl as its temperature lowered, so it was an exothermic reaction for the HCL.
Heat was gained by water as its temperature increased, so it was an endothermic reaction for the water.
m = Mass of water = 100 g
c = Specific heat of water = 
= Change in temperature of water = 
Heat is given by

Heat gained by water is
.
Answer: Option (c) is the correct answer.
Explanation:
It is known that when we tend to dilute an impure product with too much of solvent then it will lead to dissolution of the solute. As a result, the chances of formation of crystal reduces.
And, when we increase the temperature then there will occur increase in the number of collisions between the solute and solvent molecules.
Hence, solubility of the solute also increases with increase in temperature, placing it on ice bath will further reduce the crystal formation, hence no crystal should be formed in the reaction.
Thus, we can conclude that the result of crystals boiling the impure product with too much solvent and then cooling on ice is that no crystals are produced.
See , from the equation we can see that for forming two mole of H2O 2Mole of H2 has to react.
Mass of 2 Mole H2O is 18*2gm or 36gm.
So for forming 36 gm H2O 2×2 I.e. 4 gm H2 has to take part in reaction.
Therefore, to form 1 gm H2O 4÷36 gm of H2 has to take part.
So, for forming 47gm H2O (4÷36)×47 gm H2 has to take part
I.e. 5.22 gm of H2 has to take part
So, ans is 5.22 gm of hydrogen.
Hope it helps!!!