When $[\text{Cr}(\text{NH}_3)_6]\text{Cl}_3$ dissolves in water, the three chloride ions present outside the coordination sphere ionise completely:

This yields $1$ complex cation $[\text{Cr}(\text{NH}_3)_6]^{3+}$ and $3$ chloride anions $\text{Cl}^-$, giving a total of $1 + 3 = 4$ ions.

Number of molecules $N = n \times N_A = \left(\frac{\text{Mass}}{\text{Molar mass}}\right) \times N_A$:

• For $\text{H}_2$: Molar mass $= 2\text{ g mol}^{-1} \implies n = \frac{16}{2} = 8.0\text{ mol}$
• For $\text{CO}$: Molar mass $= 28\text{ g mol}^{-1} \implies n = \frac{16}{28} \approx 0.57\text{ mol}$
• For $\text{O}_2$: Molar mass $= 32\text{ g mol}^{-1} \implies n = \frac{16}{32} = 0.50\text{ mol}$
• For $\text{CO}_2$: Molar mass $= 44\text{ g mol}^{-1} \implies n = \frac{16}{44} \approx 0.36\text{ mol}$

Decreasing order of moles (and hence molecules): $\text{H}_2\text{ (D)} \gt \text{CO}\text{ (C)} \gt \text{O}_2\text{ (A)} \gt \text{CO}_2\text{ (B)}$.

For an association equilibrium $n\text{X} \rightleftharpoons (\text{X})_n$, the van 't Hoff factor ($i$) is related to the degree of association ($\alpha$) by:

Given $i = 0.80$ and $\alpha = 0.3$:

In $[\text{Co}(\text{en})_3]_2(\text{SO}_4)_3$:

• Ethane-1,2-diamine ($\text{H}_2\text{NCH}_2\text{CH}_2\text{NH}_2$, abbreviated as en) is a neutral bidentate ligand (charge $= 0$).
• Sulphate ion ($\text{SO}_4^{2-}$) has a charge of $-2$.

Let the oxidation state of cobalt be $x$:

By convention, peptides are written starting from the N-terminal amino acid on the left to the C-terminal amino acid on the right.
In Gly-Ala (glycylalanine):

• Glycine ($\text{H}_2\text{N}-\text{CH}_2-\text{COOH}$) provides the free $-\text{NH}_2$ group and participates via its $-\text{COOH}$ group.
• Alanine ($\text{H}_2\text{N}-\text{CH}(\text{CH}_3)-\text{COOH}$) participates via its $-\text{NH}_2$ group and provides the free $-\text{COOH}$ group.

Combining them yields $\text{H}_2\text{N}-\text{CH}_2-\text{CO}-\text{NH}-\text{CH}(\text{CH}_3)-\text{COOH}$.