Determine the enthalpy:
4nh3(g) + 7o2(g) −→ 4no2(g) + 6h2o(ℓ)

∆h◦ f species ( kj mol)
nh3(g) −46.11
no2(g) +33.2
h2o(ℓ) −285.83

1. −1899 kj/mol rxn
2. +2034.4 kj/mol rxn
3. −298.7 kj/mol rxn
4. −1766 kj/mol rxn
5. −1397.6 kj/mol rxn

The enthalpy change of the reaction −1397.6 kJ/mol.

We can determine the enthalpy change of the reaction from the enthalpy of formation of each specie as follows;

∆H(reaction) = ∑∆H◦f(products) - ∑∆H◦f(reactants)

Given the following from the question;

NH3(g) = −46.11 kJ /mol

NO2(g) = +33.2 kJ /mol

H2O(ℓ) = −285.83 kJ /mol

We can now substitute values;

∆H(reaction) =   ∑(4 × 33.2) + (6 × (−285.83)) - ∑(4 × (−46.11)) + (7 × 0))  kJ /mol

The ∆H◦ f  of oxygen is zero because it is a pure substance.

∆H(reaction) = (132.8 - 1714.98) - (-184.44 + 0) kJ /mol

∆H(reaction) =−1397.6 kJ/mol

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Choice 5.: -1397.6 kJ/mol rxn.

Explanation:

Here's how to find the enthalpy change of a reaction from the standard enthalpy of formation of each species.

for the most stable allotrope of each elements under their standard state. For example,

As a result, for . Note the gaseous state symbol. This value is implied such that it's not provided in the question.

For this reaction:

.

.

Apply the equation:

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yes, water is wet, just as it makes other things wet, it is wet itself, kinda like ice, when ice is in water, the ice makes water cold, and ice is cold, therefore with that example, water is wet

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.