Which of the following reactions is known as slaking of lime?

Q. Identify the endothermic and exothermic reaction.
a. HCl + NaOH → NaCl + H₂O + heat
b. $2{\mathrm{KClO}}_3\left(\mathrm{s}\right)\stackrel{∆}{\to }2\mathrm{KCl}\left(\mathrm{s}\right)+3{\mathrm{O}}_2\uparrow$
c. CaO + H₂O → Ca(OH)₂ + heat
d. $Ca{\mathrm{CO}}_3\left(\mathrm{s}\right)\stackrel{∆}{\to }CaO\left(\mathrm{s}\right)+{\mathrm{CO}}_2\uparrow$

Q. A process designed to remove organic sulphur from coal prior to combustion involves the reaction.
$X-S-Y+2NaOH\to X-O-Y+N{a}_{2}S+H_{2}O$
$CaC{O}_3\to CaO+C{O}_2$
$N{a}_{2}S+C{O}_2+H_{2}O\to N{a}_{2}C{O}_3+H_{2}S$
$CaO+H_{2}O\to Ca(OH{)}_2$
$N{a}_{2}C{O}_3+Ca(OH{)}_2\to CaC{O}_3+2NaOH$
In the processing of 320 metric tons of a coal having 1.0% sulphur content, how much limestone $\left(CaC{O}_3\right)$must be edecomposed to provide enough $Ca(OH{)}_2$ to regenerate the NaOH used in the original leaching step?

Q. The chemical reactions involved in the ammonia soda process are represented as follows:
$2NaCl+CaC{O}_3\to N{a}_{2}C{O}_3+CaC{l}_2$
In the following reactions,
$CaC{O}_3\stackrel{\Delta }{\to }\left[A\right]+\left[B\right]$
$NaCl+N{H}_3+\left[B\right]+H_{2}O\to \left[C\right]+\left[D\right]$
$2\left[C\right]\to N{a}_{2}C{O}_3+H_{2}O+\left[B\right]$
Identify A to D: