Answer:
0.78 m
Explanation:
The relationship between wavelength and frequency of a wave is given by

where
v is the speed of the wave
f is the frequency
is the wavelength
For the sound wave in this problem, we have
is the frequency
v = 344 m/s is the speed of sound in air
Substituting into the equation and re-arranging it, we find the wavelength:

The element is iridium and it has 77 electrons
We Know, Power = Energy/Time
Substitute the known value. which is P = 350 watt, & T = 30 sec
350 = E/30
E = 350 * 30
E = 1050 Joules.
So, your answer is 1050 Joules.
Hope this helps! Keep studying!