Answer : The value of ΔH for this reaction is, -1516 kJ/mol
Explanation :
First we have to calculate the moles of 
Now we have to calculate the ΔH for this reaction.
As, 2.5 mole of react to gives heat = -3790 kJ
So, 1 mole of react to gives heat = 
= -1516 kJ/mol
Therefore, the value of ΔH for this reaction is, -1516 kJ/mol
In a precipitation reaction, one of the product formed is an insoluble precipitate.
The given reactions can be written with phases included as:
A. 
: In this reaction one of the product, FeS is insoluble. Therefore, this is a precipitation reaction.
B. 
: In this reaction, the product 
is a solid(insoluble). So, this is a precipitation reaction too.
C.
: In this reaction, both the products are soluble. So this is not a precipitation reaction.
D.
: In this reaction, both the products are soluble. So this is not a precipitation reaction.
E. 
: In this reaction, the product AgCl is a precipitate. So, it is a precipitation reaction.
In the Lewis symbol for a sulfur atom, there are four (4) paired and two (2) unpaired electrons.
Sulfur electron configuration: ₁₆S 1s²2s²2p⁶3s²3p⁴.
Sulfur has six valence electrons (3s²3p⁴), in 3s orbital, two electrons are paired, in 3p orbital, two electrons are paired and two are unpaired.
