Answer
1029 m
Step-by-step explanation
In a thunderstorm the thunderclap is always heard after some seconds of lightning because speed of light and speed of sound is different in the air though these both incident took place at the same time.
Sound in air travels at approximately 343 m/s at 20°C
The speed of light in air is to 3 x 10⁸ m/s at 20°C
Formula to use
distance = speed x time
= 3 x 343
= 1029 m