Answer:

Explanation:
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In this case, since the standard enthalpy change for a chemical reaction is stood for the enthalpy of reaction, for the given reaction:

We set up the enthalpy of reaction considering the enthalpy of formation of each species in the reaction at the specified phase and the stoichiometric coefficient:

In such a way, by using the NIST database, we find that:

Thus, we plug in the enthalpies of formation to obtain:

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Answer : The structure of
will be square-planar.
Explanation :
In the given molecule
, 'Xe' is the central atom and 'H' is the terminal atom.
Xenon has 8 valence electrons and hydrogen has 1 valence electron. Therefore, the total number of valence electrons are 8 + 4(1) = 12 electrons.
The number of electrons used in Xe-H bonding = 8 electrons
The remaining electrons which are used as lone pair on central atom (Xe) = 12 - 8 = 4 electrons
There are 4 bonding pairs and 2 lone pairs of electrons, they will be arranged in the octahedral arrangement around the central atom with 2 lone pairs of electrons on central atom. The lone pairs are arranged linearly across the central atom. The resulting structure will be square-planar.
The structure of
is shown below.