Question

Base reacts with metal to form _________________ and base reacts with non-metal oxides to form ________________.
A.Water, water
B.Water, hydrogen gas
C.Hydrogen gas, water
D.Hydrogen gas, hydrogen gas

Answer 1

Hint: Bases are substances which have a soapy texture to touch and have a bitter taste. Bases react with acids to neutralise them. Bases which are soluble in water are called alkali. Bases can react with a number of compounds to form different products.

Complete step by step solution:
All alkali are bases, but all bases are not alkali. Alkali can produce ${\text{O}}{{\text{H}}^ - }$ ions on dissolution in water.
Alkali have the ability to turn red litmus blue.
Some examples for metals are zinc ( ${\text{Zn}}$ ), copper ( ${\text{Cu}}$ ), aluminium ( ${\text{Al}}$ ) etc.
Some examples for alkali are sodium hydroxide ( ${\text{NaOH}}$ ), potassium hydroxide ( ${\text{KOH}}$ ), calcium hydroxide ( ${\text{Ca}}{\left( {{\text{OH}}} \right)_2}$ ) etc.
Reaction of base with metal
A base reacts with a metal to form salt. During the reaction of a base with metal, hydrogen gas is evolved. The evolution of hydrogen gas can be confirmed by bringing a lit candle near the mouth of the test tube. This leads to a pop sound, indicating the evolution of hydrogen gas.
${\text{Alkali + Metal }} \to {\text{ Salt + Hydrogen}}$
Examples for reaction of a base with a metal are as follows:
Sodium hydroxide on reaction with zinc metal gives sodium zincate and hydrogen gas:
${\text{Zn + 2NaOH }} \to {\text{ N}}{{\text{a}}_2}{\text{Zn}}{{\text{O}}_2}{\text{ + }}{{\text{H}}_2} \uparrow $
Sodium hydroxide on reaction with aluminium metal gives sodium aluminate and hydrogen gas:
${\text{2Al + 2NaOH + 2}}{{\text{H}}_2}{\text{O }} \to {\text{ 2NaAl}}{{\text{O}}_2}{\text{ + 2}}{{\text{H}}_2} \uparrow $
Reaction of base with non-metal oxides
Non-metal oxides are formed when a non-metal in its elemental form combines with oxygen.
For example, carbon combines with oxygen to form carbon dioxide ( ${\text{C}}{{\text{O}}_2}$ ).
${\text{C(s) + }}{{\text{O}}_2}{\text{(g) }} \to {\text{ C}}{{\text{O}}_2}(g)$
Examples for some other non-metal oxides are nitrogen dioxide ( ${\text{N}}{{\text{O}}_2}$ ) , carbon monoxide ( ${\text{CO}}$ ) , sulphur dioxide ( ${\text{S}}{{\text{O}}_2}$ ) etc.
Non-metal oxides combine with a base to produce salt and water. The reason behind is the acidic nature of non-metal oxides. This leads to a neutralisation reaction.
${\text{Non - metal oxide + Base }} \to {\text{ Salt + Water}}$
Examples for reaction of a base with non-metal oxides are as follows:
Sodium hydroxide reacts with carbon dioxide to form sodium carbonate and water:
${\text{2NaOH + C}}{{\text{O}}_2}{\text{ }} \to {\text{ N}}{{\text{a}}_2}{\text{C}}{{\text{O}}_3}{\text{ + }}{{\text{H}}_2}{\text{O}}$
Calcium hydroxide reacts with carbon dioxide to form calcium carbonate and water:
${\text{Ca}}{\left( {{\text{OH}}} \right)_2}{\text{ + C}}{{\text{O}}_2} \to {\text{CaC}}{{\text{O}}_3}{\text{ + }}{{\text{H}}_2}{\text{O}}$

Hence, option (C) is the correct answer.

Note:
Remember that metal oxides are basic in nature, whereas non-metal oxides are acidic in nature. So, when metal oxides combine with acids, they produce salt and water and when non-metal oxides react with bases to produce salt and water.