(a(i))[1]
Write an equation for the reaction of limewater with $\text{CO}_2$.
(a(ii))[1]
Explain why a saturated solution of $\text{Ba(OH)}_2$ can be used for testing $\text{CO}_2$.
(a(iii))[2]
Explain why a saturated solution of $\text{Mg(OH)}_2$ cannot be used for testing $\text{CO}_2$.
(b)[3]
Describe and explain the pattern in the thermal stability of the carbonates down Group 2.
(c)[2]
Nickel carbonate, $\text{NiCO}_3$, decomposes on heating. Use the Data Booklet to explain whether $\text{NiCO}_3$ will decompose more readily or less readily than $\text{CaCO}_3$.