Question

An aqueous solution of borax is :
(A) neutral
(B) acidic
(C) basic
(D) none

Answer 1

A substance will be known as an acid if it gives out positive hydrogen ions that is ${H^ + }$ ions when dissolved in water. A substance will be known as a base if it gives out hydroxide ions that is $O{H^ - }$ ions when dissolved in water. A substance will be known as a neutral substance if it does not give out any kind of ions. To solve this question, check what borax gives on dissolving in water.

Complete Step by step solution:
Borax is known by the following names; sodium borate, sodium tetraborate or disodium tetraborate. The molecular formula for borax is $N{a_2}{B_4}{O_7}.10{H_2}O$ . The 10 ${H_2}O$ molecules present in borax are the molecules of water of crystallization. In many detergents, cosmetics and enamel glazes borax is used as a main component. In biochemistry, it is used to make a buffer solution.
The reaction that takes place when borax is dissolved in water is given as follows,
${B_4}{O_7}^{2 - } + 7{H_2}O \to 4{H_3}B{O_3} + 2O{H^ - }$
The aqueous solution of borax is weakly basic because it ionizes and produces hydroxide ions that are $O{H^ - }$ ions. Hence the aqueous solution of borax is basic.
Therefore, the correct answer is option C.

Note:
In household laundry and cleaning products, borax is used. As a flux, the mixture of borax and ammonium chloride is used. Also, borax is a component of glass, pottery as well as ceramics. To control pH, borax is used as a buffering agent in a swimming pool. In taxidermy, it is used as a preservative.