What is the value of capacitance that must be connected in parallel with 50 pF condenser to make an equivalent capacitance of 150 pF ?

The correct answer is B. 100 pF.

To calculate the equivalent capacitance of two capacitors connected in parallel, we use the following formula:

$C_{eq} = C_1 + C_2$

In this case, we are given that $C_1 = 50\text{ pF}$ and we want to find $C_2$ such that $C_{eq} = 150\text{ pF}$. Substituting these values into the formula, we get:

$150\text{ pF} = 50\text{ pF} + C_2$

Solving for $C_2$, we get:

$C_2 = 150\text{ pF} – 50\text{ pF} = 100\text{ pF}$

Therefore, the value of capacitance that must be connected in parallel with 50 pF condenser to make an equivalent capacitance of 150 pF is 100 pF.

The other options are incorrect because they do not result in an equivalent capacitance of 150 pF.