Answer : The enthalpy change of reaction is -1800 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given final reaction is,

The intermediate balanced chemical reaction will be,
(1)

(2)

First we will multiply reaction 1 by 2 and reverse reaction of reaction 2 by 3 then adding both the equation, we get :
The expression for final enthalpy is,
![\Delta H=[n\times \Delta H_1]+[n\times (-\Delta H_2)]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5Bn%5Ctimes%20%5CDelta%20H_1%5D%2B%5Bn%5Ctimes%20%28-%5CDelta%20H_2%29%5D)
where,
n = number of moles
![\Delta H=[2mole\times (-1680kJ/mole)]+[3\times -(-520kJ/mole)]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5B2mole%5Ctimes%20%28-1680kJ%2Fmole%29%5D%2B%5B3%5Ctimes%20-%28-520kJ%2Fmole%29%5D)

Therefore, the enthalpy change of reaction is -1800 kJ
Answer:

<h2>10.5 gram(cm)^-3 is the right answer.</h2>
The correct answer would be we have no other frame of reference besides the sky. We could actually tell we are moving because of the shifting of stars in the sky over time. But really, “A” would be your answer. We have the same momentum of the earth. It’s like being on a train at a constant speed. The only way you know you’re moving is if you look out the window or the speed changes causing you to be pushed around. Same thing with earth, our only reference is the sky
Answer: C) The concentration of HI will increase as the system approaches equilibrium.
Explanation:
Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as 
K is the constant of a certain reaction when it is in equilibrium, while Q is the quotient of activities of products and reactants at any stage other than equilibrium of a reaction.
For the given chemical reaction:

The expression for
is written as:
![Q_c=\frac{[HI]^2}{[H_2]^1[I_2]^1}](https://tex.z-dn.net/?f=Q_c%3D%5Cfrac%7B%5BHI%5D%5E2%7D%7B%5BH_2%5D%5E1%5BI_2%5D%5E1%7D)



Thus as
, the reaction will shift towards the right i.e. towards the product side.