So multiply number of moles x number of atoms/mole = 1.8066 x 10^24 atoms of H2. One mole of any gas at STP has a volume of 22.4 L. So first determine the number of moles of gas you have.
for example do 7

that 's what I think
3 elements are present in HCOOH - hydrogen, oxygen, and carbon.
KH₂PO₄ hydrolyzes as;
H₂PO₄⁻ + H₂O ↔ H₃PO₄ + OH⁻
Let x amount of H₂PO₄⁻ has reacted with water then,
Kb₁ = [H₃PO₄][OH⁻] / [H₂PO₄⁻]
[H₂PO₄⁻] = 0.8-x M
Kb₁ = x² / (0.8 - x)
Given Ka₁ = 7.5 x 10⁻³
so Kb₁ = 1 x 10⁻¹⁴ / (7.5 x 10⁻³) = 1.33 x 10⁻¹²
From this information:
1.33 x 10⁻¹² = x² / 0.8
x = [OH⁻] = 1.03 x 10⁻⁶ M
pOH = - log (1.03 x 10⁻⁶) = 5.99
pH = 14 - pOH = 14 - 5.99 = 8.01
1 mole has 6.02*10^23 molecules in it.
1 nickel (II) chloride molecule, NiCl2, has 1 Ni atom in it.
so 1 mole of nickel (II) chloride molecule has 1 mole of Ni atom in it.
so 100 moles of nickel (II) chloride molecule has 100*6.02*10^23
= 6.02*10^25 Ni atom in it.
Vinegar is an heterogeneous mixture
Explanation: