Answer:
the frequency of the second harmonic of the pipe is 425 Hz
Explanation:
Given;
length of the open pipe, L = 0.8 m
velocity of sound, v = 340 m/s
The wavelength of the second harmonic is calculated as follows;
L = A ---> N + N--->N + N--->A
where;
L is the length of the pipe in the second harmonic
A represents antinode of the wave
N represents the node of the wave

The frequency is calculated as follows;

Therefore, the frequency of the second harmonic of the pipe is 425 Hz.
Answer:
The longest wavelength of light that is capable of ejecting electrons from that metal is 1292 nm.
Explanation:
Given that,
Wavelength = 400 nm
Energy 
We need to calculate the longest wavelength of light that is capable of ejecting electrons from that metal
Using formula of energy


Put the value into the formula



Hence, The longest wavelength of light that is capable of ejecting electrons from that metal is 1292 nm.
Once all hydrogen is depleted the star begins to die