31.
Which of the following cannot be used as a test for $${H_2}{O_2}?$$ A
A paper dipped in $$PbS$$ (black) turns white when brought in contact with $${H_2}{O_2}.$$
B
It liberates iodine from $$KI$$ solution which gives blue colour with starch solution.
C
It gives blue colour with $${K_4}\left[ {Fe{{\left( {CN} \right)}_6}} \right].$$
D
It decolourises acidified $$KMn{O_4}$$ solution.
Answer :
It gives blue colour with $${K_4}\left[ {Fe{{\left( {CN} \right)}_6}} \right].$$
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It does not give blue colour with $${K_4}\left[ {Fe{{\left( {CN} \right)}_6}} \right].$$
32.
The $$H - O - H$$ angle in water molecule is about A
$${90^ \circ }$$
B
$${180^ \circ }$$
C
$${102^ \circ }$$
D
$${105^ \circ }$$
Answer :
$${105^ \circ }$$
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$$H - O - H$$ angle in water is slightly less than the typical tetrahedral angle. It is $${104.5^ \circ }.$$
33.
The process of production of syngas from sewage, saw-dust, scrap wood, etc. is quite common these days. The production of syngas from coal is called A
carbonisation
B
water gas shift
C
coal gasification
D
synthesis gas shift
Answer :
coal gasification
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The process of producing syngas from coke or coal is called 'coal gasification'.
34.
Only one element of __________ forms hydride. A
group 6
B
group 7
C
group 8
D
group 9
Answer :
group 6
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From group 6, only one element i.e., chromium forms hydride $$(CrH).$$
35.
Heavy water is obtained by A
boiling water
B
heating $${H_2}{O_2}$$
C
prolonged electrolysis of $${H_2}O$$
D
all of these
Answer :
prolonged electrolysis of $${H_2}O$$
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$${D_2}O$$ is prepared by repeated electrolysis of ordinary water which contains a small amount of alkali.
36.
Which of the following properties of hydrogen is incorrect? A
Like halogens, hydrogen exists as a diatomic gas.
B
Like halogens, hydrogen exhibits - 1 oxidation state in its compounds with metals.
C
Like halogens, hydrogen is liberated at cathode.
D
The ionisation energy of hydrogen is quite close to halogens.
Answer :
Like halogens, hydrogen is liberated at cathode.
37.
A metal $$(M)$$ produces a gas $$(N)$$ on reaction with alkalies like $$NaOH$$ and $$KOH.$$ Same gas is produced when the metal reacts with dilute sulphuric acid. Gas $$(N)$$ reacts with another toxic gas $$(P)$$ to form methanol at high temperature and pressure. $$(N)$$ also reacts with metals like $$(Q)$$ to form electrovalent hydrides. $$M, N, P$$ and $$Q$$ respectively are A
$$Zn,{H_2},CO,Na$$
B
$$Na,{H_2},C{l_2},Ca$$
C
$$Al,{H_2},{H_2}S,B$$
D
$$Mg,{H_2},N{O_2},Al$$
Answer :
$$Zn,{H_2},CO,Na$$
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$$\eqalign{
& \mathop {Zn}\limits_{\left( M \right)} + 2NaOH \to N{a_2}Zn{O_2} + \mathop {{H_2}}\limits_{\left( N \right)} \cr
& Zn + {H_2}S{O_4} \to ZnS{O_4} + {H_2} \cr} $$
38.
Barium peroxide reacts with phosphoric acid to produce barium phosphate along with A
water
B
hydrogen peroxide
C
dioxygen
D
phosphine
Answer :
hydrogen peroxide
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\[\underset{\begin{smallmatrix}
\text{Barium} \\
\text{peroxide}
\end{smallmatrix}}{\mathop{3Ba{{O}_{2}}}}\,+\underset{\begin{smallmatrix}
\text{Phosphoric} \\
\text{acid}
\end{smallmatrix}}{\mathop{2{{H}_{3}}P{{O}_{4}}}}\,\to \underset{\begin{smallmatrix}
\text{Barium} \\
\text{phosphate}
\end{smallmatrix}}{\mathop{B{{a}_{3}}{{\left( P{{O}_{4}} \right)}_{2}}}}\,+3\underset{\begin{smallmatrix}
\text{Hydrogen} \\
\text{peroxide}
\end{smallmatrix}}{\mathop{{{H}_{2}}{{O}_{2}}}}\,\]
39.
Which of the following hydrides is electron deficient? A
$$NaH$$
B
$$Ca{H_2}$$
C
$$C{H_4}$$
D
$${B_2}{H_6}$$
Answer :
$${B_2}{H_6}$$
40.
Hydrogen can be fused to form helium at A
high temperature and high pressure
B
high temperature and low pressure
C
low temperature and high pressure
D
low temperature and low pressure
Answer :
high temperature and high pressure
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A fusion reaction between hydrogen nuclei is difficult because positively charged nuclei repel each other. However, at very high temperatures of the order of $${10^6}$$ to $${10^7}K,$$ the nuclei may have sufficient energy to overcome the repulsive forces and thus fuse. This is why, fusion reactions are also called thermonuclear reactions.