Metals and Non-Metals
Q67. Saloni took a piece of burning charcoal and collected the
gas evolved in a test tube.
(a) How will she find the nature of the gas?
(b) Write down word equations of all the reactions taking place
in this process.
a few drops of water in the test tube containing gas. Now, cover
the test tube and shake well. After shaking, test the solution with blue litmus
and red litmus. It will turn blue litmus red. Thus, the gas is acidic in
Charcoal reacts with oxygen to form carbon dioxide gas.
(carbon) + O2 (oxygen) → CO2
dioxide reacts with water to form carbonic acid, which turns blue litmus paper
(Carbon dioxide) + H2O (Water) → H2CO3
Q68. When an iron knife is kept dipped in blue copper sulphate
solution the solution changes to light green. Why?
What happens when a piece of iron metal is placed in copper
sulphate solution name the type of reaction involved?
Ans. When iron is placed in copper sulphate solution
for some time, then the blue colour of copper sulphate solution fades and a
red-brown coating of copper metal is deposited on the piece of iron. This
reaction can be written as:
sulphate(CuSO4) + Iron(Fe) → Iron
sulphate(FeSO4) + copper(Cu)
Blue solution Greenish
the solution turns greenish due to the formation of iron sulphate. In this
reaction, a more reactive metal ‘iron’ is displaces a less reactive metal
‘copper’ from its salt solution, copper sulphate solution.
Q69. Explain how metals and non-metals produce oxides with
magnesium burns in air, it combines with the oxygen of air to form magnesium
oxide (which is basic in nature).
+ Oxygen(O2) → Magnesium oxide(MgO)
(A basic oxide)
oxide dissolves partially in water to form magnesium hydroxide solution.
oxide(MgO) + Water(H2O) → Magnesium
hydroxide turns red litmus blue. This shows that it is a base and magnesium
oxide is a basic oxide.
sulphur burns in air, it combines with oxygen of air to form sulphur dioxide
(which is an acidic oxide).
+ Oxygen(O2) → Sulphur dioxide(SO2)
dioxide dissolves in water to form sulphurous acid solution.
dioxide(SO2) + Water(H2O) → Sulphurous
sulphurous acid turns blue litmus to red showing that it is an acid and that
sulphur dioxide is acidic in nature.