Question

0.45 g of acid molecular weight 90 is neutralized by 20 mL of 0.5N caustic potash. The basicity of the acid is:

• A. 1
• B. 2
• C. 3
• D. 4

Hint:

Basicity is calculated as the number of replaceable hydrogen ions per molecule of acid, and can be found using neutralization data.

Answer 1

The Correct Option is B

Step 1: Calculate the equivalent weight of the acid.
The number of equivalents of acid is given by: \[ \text{equivalents of acid} = \frac{\text{mass of acid}}{\text{equivalent weight of acid}} = \frac{0.45 \, \text{g}}{45 \, \text{g/equivalent}} = 0.01 \, \text{equivalents}. \]
Step 2: Use the formula for neutralization.
The amount of base required for neutralization is: \[ \text{equivalents of base} = \text{normality} \times \text{volume} = 0.5 \times 0.02 = 0.01 \, \text{equivalents}. \] The basicity (number of replaceable hydrogen ions per molecule) is 2. Thus, the correct answer is (2).