Choice C.
That's when convection stops.
Where are the answers to this question?
Answer:

T=157.06 N
Explanation:
Given that
Mass of first block = 21.1 kg
Mass of second block = 12.9 kg
First mass is heavier than first that is why mass second first will go downward and mass second will go upward.
Given that pulley and string is mass less that is why both mass will have same acceleration.So lets take their acceleration is 'a'.
So now from force equation

21.1 x 9.81 - 12.9 x 9.81 =(21.1+12.9) a

Lets tension in string is T


T=21.1(9.81-2.36) N
T=157.06 N
Answer:
67.1 atm
Explanation:
From Dalton's law of Partial Pressures, the total partial pressure equals the sum of the individual partial pressures.
P = P₁ + P₂ + P₃
P₁ = 38.39 atm of O₂
P₂ = 3.38 atm of He
P₃ = 25.33 atm of N₂
So, P = P₁ + P₂ + P₃ = 38.39 atm + 3.38 atm + 25.33 atm = 67.1 atm