Answer:
The energy is 
(a) is correct option
Explanation:
Given that,
Energy = 4480 j
Weight of nitrogen = 20 g
Boil temperature = 77 K
Pressure = 1 atm
We need to calculate the internal energy
Using first law of thermodynamics


Put the value into the formula



We need to calculate the number of molecules in 20 g N₂
Using formula of number of molecules

Put the value into the formula


We need to calculate the energy
Using formula of energy

Put the value into the formula


Hence, The energy is 
<h2>
<u>Required</u><u> </u><u>Answer</u><u>:</u></h2>
The body will <u>stay at rest </u>(Option D). It is because a force of magnitude 50 N is pulled towards left and another force is pulling it towards right with same magnitude 50 N. So, the direction of force is opposite and magnitude is same i.e. 50 N. So, they will cancel each other and net force is 0. Hence, there would be no acceleration.
- Option A - Showing acceleration
- Option B - Showing acceleration
- Option C - Change of direction due to Net force
Hence, these options are incorrect because they are only possible when net external force is non-zero. Staying at rest i.e. Option D means there is no motion and hence no acceleration, this shows that net force is 0
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