Gallium, due to its metal properties, which tend to conduct electricity and heat quite well.
Answer: The value of equilibrium constant for reaction is,
Explanation:
The given chemical equations are:
(1)
;
(2)
; 
Now we have to calculate the equilibrium constant for chemical equation as:
; 
We are reversing reaction 2 and multiplying reaction 2 by 2 and then adding both reaction, we get the final reaction.
The equilibrium constant for the reverse reaction will be the reciprocal of that reaction.
If the equation is multiplied by a factor of '2', the equilibrium constant of that reaction will be the square of the equilibrium constant.
If we are adding equations then the equilibrium constants will be multiplied.
The value of equilibrium constant for reaction is:

Now put all the given values in this expression, we get:


Hence, the value of equilibrium constant for reaction is,
In general terms, exothermic reactions release energy, so the energy goes from the system to the surroundings.
In order to answer this, you need to find the empirical data for the standard entropies. Please refer to this link: http://www.mrbigler.com/misc/energy-of-formation.PDF
For NO₂ gas, the entropy is 240 J/mol-K. For N₂O₄ gas, the entropy is 304.2 J/mol-K. Therefore, <em>the statement is false.</em>