<h2><em>Solid. Because molecules densely packed it has a high resistance to flow thereby lower kinetic energy.
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C. Fewer. it is a summary
Answer:
A
Explanation:
i did it before and got it right
Answer: Option (d) is the correct answer.
Explanation:
A reaction in which there occurs change in oxidation state of reacting species is known as an oxidation-reduction reaction.
(a)
Will be written as:

In this reaction, there occurs no change in oxidation state of reacting species. Hence, it is not an oxidation-reduction reaction.
(b) 
Will be written as:

Similarly here, there occurs no change in oxidation state of reacting species. Hence, it is not an oxidation-reduction reaction.
(c) 
Will be written as:

Here, also there occurs no change in oxidation state of reacting species. Hence, it is not an oxidation-reduction reaction.
(d) 
So, here there occurs change in oxidation state of Mg from 0 to +2 and oxidation state of H changes from +1 to 0. Hence, it is an oxidation-reduction reaction.
Thus, we can conclude that
is an oxidation-reduction reaction.
Answer:
Here's what I find.
Explanation:



The sign of ΔH changes when you reverse the reaction.