Balance the following chemical equations.
$(a)$ $HNO _{3}+ Ca ( OH )_{2} \longrightarrow Ca \left( NO _{3}\right)_{2}+ H _{2} O$
$(b)$ $NaOH + H _{2} SO _{4} \longrightarrow Na _{2} SO _{4}+ H _{2} O$
$(c)$ $NaCl + AgNO _{3} \longrightarrow AgCl + NaNO _{3}$
$(d)$ $BaCl _{2}+ H _{2} SO _{4} \longrightarrow BaSO _{4}+ HCl$
$(a)$ $2 HNO _{3}+ Ca ( OH )_{2} \longrightarrow Ca \left( NO _{3}\right)_{2}+2 H _{2} O$
$(b)$ $2NaOH + H _{2} SO _{4} \longrightarrow Na _{2} SO _{4}+ 2H _{2} O$
$(c)$ $NaCl + AgNO _{3} \longrightarrow AgCl + NaNO _{3}$
$(d)$ $BaCl _{2}+ H _{2} SO _{4} \longrightarrow BaSO _{4}+2 HCl$
A shiny brown coloured element $‘X’$ on heating in air becomes black in colour. Name the element $‘X’$ and the black coloured compound formed.
Why does the colour of copper sulphate solution change when an iron nail is dipped in it ?
Write a balanced chemical equation with state symbols for the following reactions.
$(i)$ Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.
$(ii)$ Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.
Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.
What happens when dilute hydrochloric acid is added to iron fillings ? Tick the correct answer.