Answer : The value of 
for this reaction is 36.18 kJ
Explanation :
First law of thermodynamic : It states that the energy can not be created or destroyed, it can only change or transfer from one state to another state.
As per first law of thermodynamic,
where,
= internal energy of the system
q = heat added or rejected by the system
w = work done
As we are given that:
q = 38.65 kJ
w = -2.47 kJ (system work done on surrounding)
Now put all the given values in the above expression, we get:
Therefore, the value of for this reaction is 36.18 kJ
For 7A(17) :
Electronic configuration 
So, there are 5 unpaired electrons present in group 7A(17).
<h3>
What are Unpaired Electrons?</h3>
- An unpaired electron is an electron that doesn't form part of an electron pair when it occupies an atom's orbital in chemistry.
- Each of an atom's three atomic orbitals, designated by the quantum numbers n, l, and m, has the capacity to hold a pair of two electrons with opposing spins.
- Unpaired electrons are extremely uncommon in chemistry because an object carrying an unpaired electron is typically quite reactive. This is because the production of electron pairs, whether in the form of a chemical bond or as a lone pair, is frequently energetically advantageous.
- They play a crucial role in describing reaction pathways even though they normally only appear momentarily during a reaction on a thing called a radical in organic chemistry.
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C. the expansion of the universe is accelerating
D as the two substances could have close boiling points, so if the temperature is not controlled well, both substances will evaporate.
The ground-state electron configurations of 
transition metal ions are diamagnetic [Kr] 
. The ion is diamagnetic because there all electrons are paired.
<h3>
What is Diamagnetic?</h3>
- A magnetic field repels diamagnetic materials because it induces an opposing magnetic field in them when it is applied, which produces a repelling force.
- In contrast, a magnetic field draws paramagnetic and ferromagnetic materials together.
- All materials experience the quantum mechanical phenomenon known as diamagnetism, which is the only source of magnetism in a material.
- The magnetic dipoles within paramagnetic and ferromagnetic materials exert an attracting force that outweighs the modest diamagnetic force.
- Diamagnetic materials have a magnetic permeability that is less than vacuum, or 0.
- Although superconductors behave as strong diamagnets, diamagnetism is often a modest effect that can only be observed by sophisticated laboratory equipment.
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