Em tham khảo nha:
\(\begin{array}{l}
15)\\
{d_{S/O}} = \dfrac{{{M_S}}}{{{M_O}}} = \dfrac{{32}}{{16}} = 2\\
\Rightarrow\text{ S nặng gấp 2 lần O} \\
{d_{S/H}} = \dfrac{{{M_S}}}{{{M_H}}} = \dfrac{{32}}{1} = 32\\
\Rightarrow\text{ S nặng gấp 32 lần H} \\
{d_{S/C}} = \dfrac{{{M_S}}}{{{M_C}}} = \dfrac{{32}}{{12}} = 2,67\\
\Rightarrow\text{ S nặng gấp 2,67 lần C} \\
16)\\
{M_{Na}} = 23u\\
\Rightarrow {M_{Na}} = 23 \times 1,6605 \times {10^{ - 24}} = 3,81915 \times {10^{ - 23}}(g)\\
{M_{Al}} = 27u\\
\Rightarrow {M_{Al}} = 27 \times 1,6605 \times {10^{ - 24}} = 4,48335 \times {10^{ - 23}}(g)\\
{M_{Fe}} = 56u\\
\Rightarrow {M_{Fe}} = 56 \times 1,6605 \times {10^{ - 24}} = 9,2988 \times {10^{ - 23}}(g)\\
17)\\
{M_K} = 39(dVC)\\
{M_{Si}} = 28(dVC)\\
{M_P} = 31(dVC)\\
18)\\
\dfrac{{{M_X}}}{4} = \dfrac{{{M_K}}}{3} \Rightarrow {M_X} = \dfrac{{39}}{3} \times 4 = 52(g/mol)\\
\Rightarrow X:Crom(Cr)\\
Cr:II,III
\end{array}\)
