S - Block Elements MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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131.
Two metals $$X$$ and $$Y$$ belong to the second group of periodic table. $$X$$ forms insoluble oxide but soluble sulphate. $$Y$$ forms a soluble oxide but insoluble sulphate. Hydroxide of metal $$X$$ is soluble in $$NaOH$$ while that of metal $$Y$$ is insoluble in $$NaOH.$$ What are metals $$X$$ and $$Y?$$
132.
Calcium imide on hydrolysis gives gas $$(B)$$ which on oxidation by bleaching powder gives gas $$(C).$$ Gas $$(C)$$ on reaction with magnesium give compound $$(D)$$ which on hydrolysis gives again gas $$(B).$$ Identify $$(B), (C)$$ and $$(D).$$
A
$$N{H_3},{N_2},M{g_3}{N_2}$$
B
$${N_2},N{H_3},MgNH$$
C
$${N_2},{N_2}{O_5},Mg{\left( {N{O_3}} \right)_2}$$
D
$$N{H_3},N{O_2},Mg{\left( {N{O_2}} \right)_2}$$
Answer :
$$N{H_3},{N_2},M{g_3}{N_2}$$
$$\eqalign{
& Ca\left( {NH} \right) + 2{H_2}O \to Ca{\left( {OH} \right)_2} + \mathop {N{H_3}\left( g \right)}\limits_{\left( B \right)} \cr
& \mathop {2N{H_3}}\limits_{\left( B \right)} + 3CaOC{l_2} \to \mathop {{N_2}\left( g \right)}\limits_{\left( C \right)} + 3CaC{l_2} + 3{H_2}O \cr
& \mathop {{N_2}\left( g \right)}\limits_{\left( C \right)} + 3Mg \to \mathop {M{g_3}{N_2}}\limits_{\left( D \right)} \cr
& \mathop {M{g_3}{N_2}}\limits_{\left( D \right)} + 6{H_2}O \to 3Mg{\left( {OH} \right)_2} + \mathop {N{H_3}}\limits_{\left( B \right)} \cr} $$
133.
Which of the following statement is false ?
A
Strontium decomposes water readily than beryllium
B
$$BaC{O_3}$$ melts at a higher temperature than $$CaC{O_3}$$
C
Barium hydroxide is more soluble in water than $$Mg{\left( {OH} \right)_2}$$
D
Beryllium hydroxide is more basic than barium hydroxide
Answer :
Beryllium hydroxide is more basic than barium hydroxide
The size of beryllium is very small and the hydroxide formed by it, are amphoteric in nature, so its hydroxide is less basic than barium hydroxide.
134.
Which of the following reactions produces hydrogen?
A
$$Mg + {H_2}O$$
B
$${H_2}{S_4}{O_8} + {H_2}O$$
C
$$Ba{O_2} + HCl$$
D
$$N{a_2}{O_2} + 2HCl$$
Answer :
$$Mg + {H_2}O$$
Alkali and alkaline earth metals react with water to produce hydrogen gas and metal hydroxide. This is due to their high electropositive character.
$$Mg + 2{H_2}O \to Mg{\left( {OH} \right)_2} + {H_2}$$
135.
Which of the following are found in biological fluids $$N{a^ + },M{g^{2 + }},C{a^{2 + }},{K^ + },S{r^{2 + }},L{i^ + }$$ and $$B{a^{2 + }}?$$
A
$$M{g^{2 + }},C{a^{2 + }},\,{\text{and}}\,S{r^{2 + }}$$
B
$$N{a^{2 + }}\,{\text{and}}\,{K^ + }$$
C
$$N{a^ + },{K^ + },M{g^{2 + }}\,{\text{and}}\,C{a^{2 + }}$$
Monovalent sodium and potassium ions and divalent magnesium and calcium ions are found in large proportions in biological fluids.
136.
The formula of calcium cyanamide is
A
$$Ca{\left( {CN} \right)_2}$$
B
$$Ca{C_2}N$$
C
$$CaNCN$$
D
$$CaCHN{H_2}$$
Answer :
$$CaNCN$$
Calcium cyanamide : $$CaNCN$$
137.
If $$NaOH$$ is added to an aqueous solution of $$Z{n^{2 + }}ions,$$ a white precipitate appears and on adding excess $$NaOH,$$ the precipitate dissolves. In this solution zinc exists in the :
138.
Halides of alkaline earth metals form hydrates such as $$MgC{l_2} \cdot 6{H_2}O,CaC{l_2} \cdot 6{H_2}O,$$ $$BaC{l_2} \cdot 2{H_2}O$$ and $$SrC{l_2} \cdot 2{H_2}O.$$ This shows that halides of group 2 elements
A
are hygroscopic in nature
B
act as dehydrating agents
C
can absorb moisture from air
D
all of the above
Answer :
all of the above
Halides of alkaline earth metals are hygroscopic in nature, act as dehydrating agent and can absorb moisture from air.
139.
Sodium is made by the electrolysis of a molten mixture of about $$40\% \,\,NaCl$$ and $$60\% \,\,CaC{l_2}$$ because
A
$$C{a^{2 + }}$$ can reduce $$NaCl$$ to $$Na$$
B
$$C{a^{2 + }}$$ can displace $$Na$$ from $$NaCl$$
C
$$CaC{l_2}$$ helps in conduction of electricity
D
this mixture has a lower melting point than $$NaCl$$
Answer :
this mixture has a lower melting point than $$NaCl$$
The melting point of sodium chloride is high, so to reduce the melting point of $$NaCl$$ some $$CaC{l_2}$$ is added to the electrolytic mixture.
140.
Which among the following is kinetically inert towards water?
A
$$Na$$
B
$$Be$$
C
$$Ca$$
D
$$K$$
Answer :
$$Be$$
$$Na, K$$ and $$Ca$$ decompose water by evolving hydrogen gas. However $$Be$$ does not react with water even when red hot. Its protective oxide layer survives even at high temperature.