(a) Represent the statement in word equation
Sodium carbonate + Hydrochloride acid \(\rightarrow\) Sodium chloride + Water Carbon dioxide
(b) Give the formula to the word equation Na₂CO₃+HCl\(\rightarrow\)NaCl+H₂O+CO₂
(c) Balance the equation.
Na₂CO₃ + 2HCl \(\rightarrow\) 2NaCl + H₂O + CO₂
(d) Write the physical states
Na2CO₃(s)+2HCl(aq)\(\rightarrow\) 2NaCl(s)+H₂O(l)+CO₂(g)

(a) When magnesium is heated in oxygen of air, it leaves white powder of magnesium oxide which dissolves in water. The magnesium oxide being alkaline in nature turns red litmus to blue. Also, the metal in ribbon form is Magnesium [Mg]. Thus 'X' is identified ad magnesium and 'Y' is identified as magnesium oxide.
(b)The chemical reaction is:
2Mg(s)+O₂(g)\(\rightarrow\)2MgO

The above reaction is a decomposition reaction. The symbol \(\Delta\) represents the heat and the MnO₂ represents that it acts as a catalyst for the decomposition reaction to take place. Since the decomposition takes place in presence of heat, the reaction is thermal decomposition.

A substance 'A' which displaces 'B' from its solution in water must be higher in reactivity. Therefore, 'A' must be high reactivity metal, let us say zinc(Zn). The 'B' must be copper sulphate solution. This is because copper is least reactive than zinc.
CuSO₄+Zn\(\rightarrow\)ZnSO₄+Cu
In this reaction, zinc is oxidised to zinc sulphate and copper sulphate is reduced to copper metal. Thus this reaction is also called redox reaction.

The yellowish compound is silver bromide [AgBr].
When silver bromide is exposed to sun light, it produces a grey coloured silver metal.
\(2AgBr\longrightarrow2Ag+Br_2\)
Thus 'A' is silver bromide [AgBr], 'B' is silver metal [Ag] and 'C' is bromine [Br₂]
The nitrate of 'B' is silver nitrate [AgNO3]
Silver nitrate when treated with sodium bromide, it forms silver bromide.
AgNO₃+NaBr\(\rightarrow\)AgBr+NaNO₃