what happens to the yield of hydrogen if the reaction is carried out at a higher pressure but at the same temperature

The yield of hydrogen decreases

Explanation:

The Haber process is exothermic. The equation of the Haber process is;

N2(g) + 3H2(g) > 2NH3(g)    ΔH = -ve

Now, if we maintain a constant temperature, the number of volumes will affect the yield of products as follows;

The higher the pressure the lesser yield of hydrogen because the increase in pressure shifts the equilibrium position towards the right hand side.

the answer is learned

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.