In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.
$\mathop {2AgN{O_{3(aq)}}}\limits_{Silver{\text{ }}nitrate} + \mathop {C{u_{(s)}}}\limits_{Copper} \to \mathop {Cu{{\left( {N{O_3}} \right)}_{2\left( {aq} \right)}}}\limits_{Copper{\text{ }}nitrate} + \mathop {2A{g_{(s)}}}\limits_{Silver} $
Identify the substances that are oxidised and the substances that are reduced in the following reactions.
$(i)$ $4 Na ( s )+ O _{2}( g ) \rightarrow 2 Na _{2} O ( s )$
$(ii)$ $CuO ( s )+ H _{2}( g ) \rightarrow Cu ( s )+ H _{2} O ( l )$
Why is the amount of gas collected in one of the test tubes in image double of the amount collected in the other ? Name this gas.
What do you mean by a precipitation reaction? Explain by giving examples.
Translate the following statements into chemical equations and then balance them.
$(a)$ Hydrogen gas combines with nitrogen to form ammonia.
$(b)$ Hydrogen sulphide gas burns in air to give water and sulpur dioxide.
$(c)$ Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
$(d)$ Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.
Which of the statements about the reaction below are incorrect ?
$2 PbO _{( s )}+ C _{( s )} \longrightarrow 2 Pb _{( s )}+ CO _{2( g )}$
$(a)$ Lead is getting reduced.
$(b)$ Carbon dioxide is getting oxidised.
$(c)$ Carbon is getting oxidised.
$(d)$ Lead oxide is getting reduced.