Answer:
Pressure
Explanation:
Basically when you are pressing something you are applying force over an area thus Pressure is force divided by area.
Answer:
Energy is added (postive enthalpy)
Explanation:
Ice melting means solid turns into liquid. Solid is more stable than liquid thus you must put in energy to weaken the forces of solid and turn it into liquid. Thus, you must put in energy to melt ice. This makes the enthalpy of the system to be positive.
Answer:

Explanation:
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In this case, according to the given information it will be firstly necessary to set up the chemical equation taking place:

We infer we need to calculate the moles of NH3 by using both of the moles of N2 and H2 at the beginning, in order to identify the limiting reactant:

Thus, since hydrogen yields the fewest moles of ammonia, we conclude that we are just able to yield 4 moles of NH3.
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In a neutral ionic compound, you can determine its sub-scripts by simply flipping the ionic charges and dropping the signs: so AlS would be Al2S3
the second one, any change in a DNA gene or chromosome