381. In silicon dioxide
A
there are double bonds between silicon and oxygen atoms
B
silicon atom is bonded to two oxygen atoms
C
each silicon atom is surrounded by two oxygen atoms and each oxygen atom is bonded to two silicon atoms
D
each silicon atom is surrounded by four oxygen atoms and each oxygen atom is bonded to two silicon atoms.
Answer :
each silicon atom is surrounded by four oxygen atoms and each oxygen atom is bonded to two silicon atoms.
382.
A metal $$X$$ reacts with aqueous $$NaOH$$ solution to form $$Y$$ and a highly inflammable gas. Solution $$Y$$ is heated and $$C{O_2}$$ is poured through it. $$Z$$ precipitates out and $$N{a_2}C{O_3}$$ is formed. $$Z$$ on heating gives $$A{l_2}{O_3}.$$ Identify $$X, Y$$ and $$Z.$$
$$X$$
$$Y$$
$$Z$$
(a)
$$Al$$
$$NaAl{O_2}$$
$$Al{\left( {OH} \right)_3}$$
(b)
$$A{l_2}{O_3}$$
$$NaAl{O_2}$$
$$A{l_2}C{O_3}$$
(c)
$$A{l_2}{O_3}$$
$${\left[ {N{a_2}Al{O_2}} \right]^ + }O{H^ - }$$
$$Al{\left( {OH} \right)_3}$$
(d)
$$Al$$
$$Al{\left( {OH} \right)_3}$$
$$A{l_2}{O_3}$$
A
(a)
B
(b)
C
(c)
D
(d)
Answer :
(a)
383.
Phosphorous acid on heating gives the following products : \[4{{H}_{3}}P{{O}_{3}}\xrightarrow{\Delta }3{{H}_{3}}P{{O}_{4}}+P{{H}_{3}}\]
The above reaction is an example of
A
oxidation
B
thermal decomposition
C
disproportionation
D
reduction
Answer :
disproportionation
384. Aluminium chloride exists as dimer, $$A{l_2}C{l_6}$$ in solid state as well as in solution of non-polar solvents such as benzene. When dissolved in water, it gives
A
$${\left[ {Al{{\left( {OH} \right)}_6}} \right]^{3 - }} + 3HCl$$
B
$${\left[ {Al{{\left( {{H_2}{O}} \right)}_6}} \right]^{3 + }} + 3C{l^ - }$$
C
$$A{l^{3 + }} + 3C{l^ - }$$
D
$$A{l_2}{O_3} + 6HCl$$
Answer :
$${\left[ {Al{{\left( {{H_2}{O}} \right)}_6}} \right]^{3 + }} + 3C{l^ - }$$
385.
Which of the following statements are incorrect?
(i) Dry slaked lime reacts with $$C{l_2}$$ to give calcium chlorate.
(ii) With excess chlorine ammonia forms nitrogen trichloride.
(iii) Sulphur reacts with $$C{l_2}$$ to give $$SC{l_4}.$$
(iv) With hot and cone. $$NaOH,C{l_2}$$ gives sodium chlorate.
A
(i) and (ii)
B
(i) and (iii)
C
(ii) and (iii)
D
(ii) and (iv)
Answer :
(i) and (iii)
386.
$$NaB{H_4} + {I_2} \to X + Y + Z$$
\[B{{F}_{3}}+NaH\xrightarrow{450\,K}X+P\]
$$B{F_3} + LiAl{H_4} \to X + Q + R$$
$$X, Y, Z, P, Q$$ and $$R$$ in the reactions are
$$X$$
$$Y$$
$$Z$$
$$P$$
$$Q$$
$$R$$
(a)
$$N{a_4}{B_4}{O_7}$$
$$NaI$$
$$HI$$
$$HF$$
$$LiF$$
$$Al{F_3}$$
(b)
$${B_2}{H_6}$$
$$NaI$$
$${H_2}$$
$$NaF$$
$$LiF$$
$$Al{F_3}$$
(b)
$${B_2}{H_6}$$
$$B{H_3}$$
$$NaI$$
$${B_3}{N_3}{H_6}$$
$$A{l_2}{F_6}$$
$$Al{F_3}$$
(c)
$$B{H_3}$$
$${B_2}{H_6}$$
$${H_2}$$
$${B_3}{N_3}{H_6}$$
$$LiF$$
$$Al{F_3}$$
A
(a)
B
(b)
C
(c)
D
(d)
Answer :
(b)
387.
In the following reaction sequence in aqueous solution, the species $$X,Y\,{\text{and}}\,Z,$$ respectively, are
\[{{S}_{2}}O_{3}^{2-}\xrightarrow{A{{g}^{+}}}\underset{\begin{smallmatrix}
\text{clear} \\
\text{solution}
\end{smallmatrix}}{\mathop{X}}\,\xrightarrow{A{{g}^{+}}}\underset{\begin{smallmatrix}
\text{white} \\
\text{precipitate }
\end{smallmatrix}}{\mathop{Y}}\,\] \[\xrightarrow{\text{with time }}\underset{\text{black precipitate }}{\mathop{Z}}\,\]
A
$${\left[ {Ag{{\left( {{S_2}{O_3}} \right)}_2}} \right]^{3 - }},A{g_2}{S_2}{O_3},A{g_2}S$$
B
$${\left[ {Ag{{\left( {{S_2}{O_3}} \right)}_3}} \right]^{5 - }},A{g_2}S{O_3},A{g_2}S$$
C
$${\left[ {Ag{{\left( {S{O_3}} \right)}_2}} \right]^{3 - }},A{g_2}{S_2}{O_3},Ag$$
D
$${\left[ {Ag{{\left( {S{O_3}} \right)}_3}} \right]^{3 - }},A{g_2}S{O_4},Ag$$
Answer :
$${\left[ {Ag{{\left( {{S_2}{O_3}} \right)}_2}} \right]^{3 - }},A{g_2}{S_2}{O_3},A{g_2}S$$
388. In graphite, electrons are
A
localised on each $$C$$-atom
B
localised on every third $$C$$-atom
C
spread out between the structure
D
Both (B) and (C)
Answer :
Both (B) and (C)
389. An aqueous solution of sodium carbonate absorbs $$NO$$ and $$N{O_2}$$ to give
A
$$C{O_2} + NaN{O_3}$$
B
$$C{O_2} + NaN{O_2}$$
C
$$NaN{O_2} + CO$$
D
$$NaN{O_3} + CO$$
Answer :
$$NaN{O_2} + CO$$
390. Which of the following is the key step in the manufacture of sulphuric acid ?
A
Burning of sulphur or sulphide ores in air to generate $$S{O_2}.$$
B
Conversion of $$S{O_2}$$ to $$S{O_3}$$ by the reaction with oxygen in presence of catalyst.
C
Absorption of $$S{O_3}$$ in $${H_2}S{O_4}$$ to give oleum.
D
Both (B) and (C).
Answer :
Conversion of $$S{O_2}$$ to $$S{O_3}$$ by the reaction with oxygen in presence of catalyst.