Đáp án:
\(\begin{array}{l}
1,B\\
2,B\\
3,B\\
4,B\\
5,A\\
6,\dfrac{{15}}{{23}}\\
7,A\\
8,B\\
9,B
\end{array}\)
Giải thích các bước giải:
1,
\(\begin{array}{l}
{M_A} = 14,285 \times 28 = 400\\
{R_2}{(S{O_4})_3} = 400\\
\to 2R + 96 \times 3 = 400\\
\to R = 56
\end{array}\)
3,
\(\begin{array}{l}
Fe + S \to FeS\\
{m_{Fe}} + {m_S} = 17,55g\\
\to {m_{Fe}}dư= 17,55 - 14,55 = 3g
\end{array}\)
6,
\(\begin{array}{l}
O:4 \times 3 \times 2 + 3 \times 2 = 30\\
\to \dfrac{{30}}{{46}} = \dfrac{{15}}{{23}}
\end{array}\)
8,
\(\begin{array}{l}
\to {n_N}:{n_O} = \dfrac{7}{{14}}:\dfrac{4}{{16}} = 1:2\\
\to N{O_2}
\end{array}\)
