Answer:
D. Exothermic.
Explanation:
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In this case, since the potential energy versus reaction progress diagrams are related to the energetic profile of a chemical reaction, we can set the initial point at the beginning of the reaction as the energy of the reactants and the final point as the energy of the products.
Next, since the change in the enthalpy of a reaction is quantified by subtracting products minus reactants, we can see that the products have less energy than the reactants and therefore ΔH for this reaction is negative, which matches with the definition of D. Exothermic reaction.
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Any chemical reaction in which the oxidation number of an atom,molecule,or ion changes by gaining or losing an electron
The balanced chemical equation between HCl and
is:

Moles of
= 
Moles of HCl required to neutralize
:

Calculating the volume of HCl from moles and molarity:

Ngl, there is no picture.
Answer:
Explanation:
To find the density of nitrogen gas at STP which is standard temperature and pressure, certain parameters must be known.
The mass of the gas must be given or its volume.
Density of a substance is the mass per unit area;
Volume of gas at STP = number of moles x 22.4
Using the volume obtained here,
Density = 
Then we can find the density.
The mass is very important.