Answer: 2 molecules of ammonia
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The balanced chemical equation for the formation of ammonia is:

According to stoichiometry,
3 molecules of hydrogen combines with 1 molecule of nitrogen to give 2 molecules of ammonia.
Colligative properties are those substances that depend
on the number of substances in the solution, not in the identity of that
substance. The property changes the way that it does when the amount of solute
is increased because it enables the solute to be scattered more. For example,
the freezing point of salt water is lower than that of the pure water due to
the salt ions present in water.
No, according to physics no work has been done.
Work must have been done by muscular force but in terms of physics no work has been done.
In physics,work is said to be done only if the force applied produced some kind of displacement in the direction of force.
In this example provided, no work has been done since the boulder doesn't get displaced,it continues to remain at its original position.
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