Question

Consider the following statements:
(a) pH of $NaCl$ solution is 7.
(b) Copper sulphate gives red colour with universal indicator.
(c) De-greesing of metals can be done with $H_{2}S{O}_4$.
Which of the above statement(s) is/are correct?

• A. Only (b)
• B. (a) and (b)
• C. (b) and (c)
• D. Only (c)

Answer 1

The correct option is B (a) and (b)

1. a. Sodium chloride it has pH of 7 in aqueous solution $NaCl$ react with $H_{2}O$ to form $NaOH$ and $HCl$ which all that products produced are a strong base and acid respectively so when $pH$ of the solution measured will be neutral at room temperature.

b. The colour will change from blue to green (neutral) to red (excess acid), with other colours in between. One can follow the rise in $pH$ with a colour chart or can use universal indicator paper or a $pH$ meter instead of the universal indicator solution.

c. De-greasing is the removal of grease and oil. De-greasing of metals can be done by NaOH.
Option B is correct.