4 Living organisms contain relatively large amounts of oxygen, carbon, hydrogen,nitrogen, and sulfur (these five elements are known as the bulk elements), along with sodium, magnesium, potassium, calcium,chlorine, and phosphorus (these six elements are known as macro minerals).
Answer:
H₂
Explanation:
To solve this question we must find, as first, find the molar mass of the homonuclear diatomic gas using Graham's law. With the molar mass we can identify this gas
<em>Graham's law:</em>

<em>Where V is the speed of the gases and m the molar mass of those:</em>
<em>As Va is 3.98 times Vb (And mB is molar mass of oxygen gas = 32g/mol)</em>

15.84 = 32g/mol / mA
mA = 2.02g/mol
As is a homonuclear diatomic gas, the molar mass of the atom is 1.01g/mol. Thus, the gas is:
<h3>H₂</h3>
Electronegativity refers to the ability of an atom to attract shared electrons in a covalent bond. The higher the value of the electronegativity, the more strongly that element attracts the shared electrons.
Number 18 is correct, number 19 is the particles speed up and the substance expands, and number 20 is decrease in volume
It’s Ca3N2 I hope this is helpful