Mass of H₂ needed to react with O₂ : 1.092 g
<h3>Further explanation</h3>
The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight / volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.
Reaction
O₂(g) + 2H₂(g) → 2H₂O(g)
mass of O₂ : 8.75 g
mol O₂(MW=32 g/mol) :

From the equation, mol ratio of O₂ : H₂ = 1 : 2, so mol H₂ :

Mass H₂ (MW=2 g/mol) :

The density is 3.144 g / cm^3.
<u>Explanation</u>:
If effective number of atom in NaCl type structure, z = 4
a = 705.2 pm ⇒ In centimeter = 705.2
10^-10
Na = 6.023
10^23
density = (molecular weight) (z) / (Na) (a^3)
where molecular weight of KI is 166 g,
Z represents the atomic number
density = (molecular weight) (z) / (Na) (a^3)
= (166
4) / (6.023
10^23)
(705.2
10^-10)
density = 3.144 g / cm^3.
It increases as temperature rises.
The answer is 1.5e+6. Hope this helped!