Answer:

Explanation:
First, we find in the tables the ΔH of formation of each compound. As you can see in the (image 1)
Then we solve the ecuation for ΔH°reaction
ΔH°reaction=∑ΔH°f(products)−∑ΔH°f(Reactants)
ΔH°reaction= (-2* 393.5 - 2*285.8) - (52.4 + 0) kJ/mol
ΔH°reaction = -1.41 *10^3 kJ/mol
Keeps in heat, protects us from radiation, provides oxygen, and protects us from objects coming towards the earth.
The answer is 9.03 × 10²⁴<span> molecules.
</span><span>Avogadro's number is the number of units (atoms, molecules) in 1 mole of substance.
Make the proportion.
</span><span>6.02 × 10²³ molecules per 1 mol
</span>x per 15 mol
6.02 × 10²³ molecules : 1 mol = x : 15 mol
x = 6.02 × 10²³ molecules * 15 mol * 1 mol
x = 90.3 × 10²³ molecules
x = 9.03 × 10 × 10²³ molecules
x = 9.03 × 10²³⁺¹ molecules
x = 9.03 × 10²⁴ molecules