Slower cooling engenders the growth of larger crystals in igneous rocks, thus, your answer should be slow cooling!
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Answer: 0.2m
Explanation: Firstly only the Rocket's Weight Compress the spring which can be found by

According to Hooks Law

The part b and c of this question is done in the attachment
I think it's false because Oxygen is diatomic so it's found as O2 which means that it has two atoms of itself.
Answer:
1.04μT
Explanation:
Due to both wires have opposite currents, the magnitude of the total magnetic field is given by

I: electric current = 10A
mu_o: magnetic permeability of vacuum = 4pi*10^{-7} N/A^2
r1: distance from wire 1 to the point in which B is measured.
r2: distance from wire 2.
The distance between wires is 40cm = 0.4m. Hence, r1=0.2m r2=0.6m
By replacing in the formula you obtain:

hence, the magnitude of the magnetic field is 1.04μT
The answer is A.
t = ( 2h / g )^1/2 = ( 2 x 6.4 / 9.8 )^1/2 = 1.14s