Question

Identify the correct sequence of relevant steps to write the formula of cupric bisulphate.

• A. 2 1 5 8
• B. 2 3 5 7
• C. 4 3 6 8
• D. 4 1 6 7

Answer 1

The correct option is B

2 3 5 7

Explanation for the correct option:

The correct sequence of relevant steps to write the formula of cupric bisulphate is as follows:

1. Writing the symbol of a positive radical as ${\mathrm{Cu}}^{+2}$
2. Writing the symbol of a negative radical as ${\mathrm{HSO}}_4^{-}$
3. Interchanging the valencies of positive and negative radicals and writing subscripts as 1 and 2.
4. Keeping HSO₄ in parenthesis

Parenthesis is required if there is more than one complexion (ion that is made up of more than one element). Here, ${\mathrm{HSO}}_4^{-}$ is a complexion and there are two of these as found out from the subscript by transposing the valency of the cation.

The explanation for the incorrect option:

As Cu is not a complexion, it is not kept in parenthesis.

The symbol of a positive radical cannot be written as ${\mathrm{Cu}}^{+}$ as this is the symbol of cuprous, not cupric.

The symbol of a negative radical cannot be written ${\mathrm{HSO}}_4^{-2}$ because it is not the symbol of bisulphate.

Interchanging the valencies of positive and negative radicals and writing subscripts as 2 and 1 is incorrect because after interchanging, the subscripts obtained for cation and anion are 1 and 2 respectively.

Hence option (b) is correct.