Answer:
B AND D
HOPE ITS HELF FUL .........
Reserves might last 53.3 years.
Earth’s mineral resources:
Answer: ??? D? dont quote me on it tho <3
Explanation:
Geothermal energy.
Electromagnetic energy originates at the sun (think UV rays; they are part of the electromagnetic spectrum). Electrical energy technically can be anywhere, as long as there are positive and negative charges. Mechanical energy is like a generator or an engine; there is always something working to get things done/made.
I hope this answer and these explanations helped!
When air is blown into the open pipe,
L = 
where nis any integral number 1,2,3,4 etc. and λ is the wavelength of the oscillation
⇒λ=
Note here that n=1 is for fundamental, n=2 is first harmonic and so on..
⇒ third harmonic will be n=4
Given L=6m, n=4, solving for λ we get:
λ=
=3m
Relationship of frequency(f), velocity of sound (c) and wavelength(λ) is:
c=f.λ Or f= 
⇒f=
≈115 Hz