Proceed with caution before crossing
Explanation:
period of pendulum = time taken for 1 oscillation = time taken for 1 complete back and forth vibration
q1 ans is given in question its 1.5 sec
q2 ans is 1.5 sec longer than 1 sec period
A highly frequency sound wave corresponds to a high pitch sound
Note: I'm not sure what do you mean by "weight 0.05 kg/L". I assume it means the mass per unit of length, so it should be "0.05 kg/m".
Solution:
The fundamental frequency in a standing wave is given by

where L is the length of the string, T the tension and m its mass. If we plug the data of the problem into the equation, we find

The wavelength of the standing wave is instead twice the length of the string:

So the speed of the wave is

And the time the pulse takes to reach the shop is the distance covered divided by the speed: