Which of the following contains the maximum number of molecules?

State whether the following statement is true or false:
$A$ mole always represents $6.023 \times 10^{22}$ atoms,molecules,or ions of a substance.

Verify by calculating that:
$(a)$ $5$ moles of $CO_2$ has a higher mass than $5$ moles of $H_2O$.
$(b)$ $120 \, g$ of calcium and $120 \, g$ of magnesium elements have a mole ratio of $3:5$.

$3.42 \, g$ of sucrose are dissolved in $18 \, g$ of water in a beaker. The number of oxygen atoms in the solution are

Give three differences between an atom and a molecule.

$(a)$ Calculate the number of moles in $112 \, g$ of iron.
$(b)$ Calculate the mass of $0.5$ mole of sugar $(C_{12}H_{22}O_{11})$.
$(c)$ Calculate the number of atoms in $8 \, g$ of oxygen $(O_2)$ molecules.
(Atomic mass of $Fe = 56 \, u, C = 12 \, u, H = 1 \, u, O = 16 \, u, N_A = 6.022 \times 10^{23} \, mol^{-1}$)