Give reason for the following:

Even though rusting is an exothermic reaction, the heat evolved when an iron nail rusts are unnoticeable.

Give reason for the following:

Electrolytic decomposition of water is a reaction involving change of state.

Give reason for the following:

A characteristic change of colour is seen when a piece of iron is added to copper [II] sulphate solution.

Give reason for the following:

The catalytic oxidation of sulphur dioxide to sulphur trioxide is represented by a double arrow [$\rightleftharpoons$] between the reactants & products, formed in the chemical reaction.

Give reason for the following:

Silver salts are kept in dark coloured bottles.

Write word equations for the following chemical reactions given below.
Also state the observation seen in each case.

${\mathrm{ZnCO}}_3\stackrel{∆}{\to }\mathrm{ZnO} + {\mathrm{CO}}_2$

Write word equations for the following chemical reactions given below.

Write word equations for the following chemical reactions given below.

$\mathrm{NaCl}+{\mathrm{AgNO}}_3\to \mathrm{AgCl}\downarrow +{\mathrm{NaNO}}_3$

Write word equations for the following chemical reactions given below.
Also state the observation seen in each case.

${\mathrm{Na}}_2{\mathrm{SO}}_3+2\mathrm{HCl}\stackrel{∆}{\to }2\mathrm{NaCl}+{\mathrm{H}}_2\mathrm{O}+{\mathrm{SO}}_2$

Write word equations for the following chemical reactions given below.
Also, state the observation seen in this case.
$2{\mathrm{SO}}_2+{\mathrm{O}}_2\rightleftharpoons 2{\mathrm{SO}}_3$