P - Block Elements MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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271.
Nitrogen dioxide and sulphur dioxide have some properties in common. Which property is shown by one of these compounds, but not by the other?
A
Forms’ acid-rain
B
Is a reducing agent
C
Is soluble in water
D
Is used as a food-preservative
Answer :
Forms’ acid-rain
(a) Nitrogen dioxide and sulphur dioxide forms acid rain. ‘Acid rain’ is the rain water containing sulphuric acid and nitric acid.
$$HN{O_2} + 2{H_2}O + {O_2} \to 4HN{O_3}$$
$$2S{O_2} + 2{H_2}O + {O_2} \to 2{H_2}S{O_4}$$
(b) $$N{O_2}$$ and $$S{O_2}$$ act as a good reducing agent e.g. $$S{O_2}$$ reduces halogens to halogen acid $$C{l_2} + 2{H_2}O + S{O_2} \to 2HCl + {H_2}S{O_4}$$
(c) $$N{O_2}$$ and $$S{O_2}$$ both are soluble in water.
(d) $$S{O_2}$$ is used in the manufacture of sodium bisulphite $$\left( {NaHS{O_3}} \right)$$ which is used as a preservative for jams, jellies and squashes.
272.
White phosphorous reacts with limited chlorine and the product is hydrolysed in the presence of water. What would be the mass of $$HCl$$ obtained
by the hydrolysis of the product formed by the reaction of $$62\,g$$ of white phosphorus with chlorine in the presence of water ?
A
200 $$g$$
B
400 $$g$$
C
219 $$g$$
D
100 $$g$$
Answer :
219 $$g$$
Phosphorus reacts with limited $$C{l_2}$$ as :
$$\eqalign{
& {P_4} + 6C{l_2} \to 4PC{l_3}\,\,\,...\left( {\text{i}} \right) \cr
& PC{l_3}\,{\text{is hydrolysed as :}} \cr
& \underline {PC{l_3} + 3{H_2}O \to {H_3}P{O_3}\left. { + 3HCl} \right] \times 4\,\,\,\,\,\,\,\,\,\,\,\,} ...\left( {{\text{ii}}} \right) \cr
& \underline {{P_4} + 6C{l_2} + 12{H_2}O \to 4{H_3}P{O_3} + 12HCl} \cr} $$
Moles of white $${P_4} = \frac{{62}}{{124}} = 0.5\,mol$$
$$1\;mol$$ of white $${P_4}$$ produces $$ = 12\,mol$$ of $$HCl$$
$$0.5\,mol$$ of white $${P_4}$$ will produce $$12 \times 0.5 = 6\,mol$$ of $$HCl$$
Mass of $$HCl = 6 \times 36.5 = 219\,g$$
273.
Extra pure $${N_2}$$ can be obtained by heating
A
$$N{H_3}\,{\text{with}}\,CuO$$
B
$$N{H_4}N{O_3}$$
C
$${\left( {N{H_4}} \right)_2}C{r_2}{O_7}$$
D
$$Ba{\left( {{N_3}} \right)_2}$$
Answer :
$$Ba{\left( {{N_3}} \right)_2}$$
$$Ba{\left( {{N_3}} \right)_2} \to Ba + 3{N_2}$$
274.
When orthophosphoric acid is heated to $${600^ \circ }C,$$ the product formed is
A
$$P{H_3}$$
B
$${P_2}{O_5}$$
C
$${H_3}P{O_3}$$
D
$$HP{O_3}$$
Answer :
$$HP{O_3}$$
When orthophosphoric acid $$\left( {{H_3}P{O_4}} \right)$$ is heated and dehydration takes place. It form metaphosphoric acid $$\left( {HP{O_3}} \right).$$
\[{{H}_{3}}P{{O}_{4}}\xrightarrow[{{600}^{\circ }}C]{\Delta }HP{{O}_{3}}+{{H}_{2}}O\]
275.
The correct statement with respect to $$CO$$ is
A
it combines with $${H_2}O$$ to give carbonic acid
B
it reacts with haemoglobin in $$RBC$$
C
it is powerful oxidising agent
D
it is used to prepare aerated drinks
Answer :
it reacts with haemoglobin in $$RBC$$
$$CO$$ react with haemoglobin, forms carboxy haemoglobin and stopes the supply of $${O_2}$$
276.
An oxide $$X$$ in its normal form is almost non-reactive due to very high $$X - O$$ bond enthalpy. It resists the attack by halogens, hydrogen and most of acids and metals even at elevated temperatures. It is only attacked by $$HF$$ and $$NaOH.$$ The oxide $$X$$ is
A
$$Si{O_2}$$
B
$$C{O_2}$$
C
$$Sn{O_2}$$
D
$$Pb{O_2}$$
Answer :
$$Si{O_2}$$
$$Si{O_2}$$ is attacked by $$HF$$ and $$NaOH$$ but not by chemicals under normal conditions.
277.
Which of the following is an isoelectronic pair?