Question

Which of the following is a highly deliquescent solid?
A. $FeC{l_3}$
B. $FeS{O_4}$
C. $CuS{O_4}$
D. All of these

Answer 1

Hint: Deliquescence is the process shown by some substances like the salts of sodium hydroxide $\left( {NaOH} \right)$potassium hydroxide $\left( {KOH} \right)$ and sodium nitrate $\left( {NaN{O_3}} \right)$ which on absorbing the atmospheric moisture forms its solution.

Complete step by step answer:
$FeS{O_4}$: It is the molecular formula for representing iron sulphate also known as green vitriol, having the medical application in treating the iron deficiencies in patients. Ferrous sulphates on association with the water forms aqua complexes ${\left[ {Fe{{\left( {{H_2}0} \right)}_6}} \right]^{2 + }}$.
$CuS{O_4}$: It is the molecular formula representing the copper sulphate which on mixing with water molecule forms ${\left[ {Cu{{\left( {{H_2}O} \right)}_6}} \right]^{2 + }}$. The number of water molecules in the copper sulphate is usually 5 which gives the blue colour to copper sulphate and on heating the water evaporates and the colour gradually changes to white.
$FeC{l_3}$: It is the molecular representation for ferric chloride having the metal in the +3 oxidation state. It has a high affinity for water molecules and forms various hydrated chloride solutions. It is the suitable example for the deliquescent solid.

Therefore, the correct option is A. .

Additional information:
$FeC{l_3}$ Undergo exothermic reactions in addition to water and produce a lot of heat. It also acts as a mild oxidizing agent due its electrode potential value which is positive and above hydrogen.

Note: Deliquescent solid are the solids that can absorb enormous amounts of water from environments and turn itself to a solution of its own, when the partial vapour pressure of atmospheric water molecules is more than that of solution formed. $FeC{l_3}$Shows the property of deliquescent solid by being attracted to water molecules present in the atmosphere so that it can form its solution.