Tuning fork A having frequency 256 Hz produce 12 beats in 2 seconds with tuning fork B. When B is loaded with wax, it produces 6 beats/sec with A. Frequency of ‘B’ before loading was

The initial frequency of tuning fork will be $256\pm 6 \mathrm{Hz}$.

On waxing the frequency of tuning fork will decrease, and since it is still making 6 beats so the frequency of tuning fork is reduced to 250 Hz from 262 Hz(original frequency).