S - Block Elements MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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171.
A metal $$M$$ reacts with nitrogen to give nitride which on reaction with water produces ammonia gas. Metal $$M$$ can be
172.
Equimolar solutions of the following were prepared in water separately. Which one of
the solutions will record the highest $$pH?$$
A
$$SrC{l_2}$$
B
$$BaC{l_2}$$
C
$$MgC{l_2}$$
D
$$CaC{l_2}$$
Answer :
$$BaC{l_2}$$
All salts are soluble in water and give strong acid and weak base
$$\eqalign{
& SrC{l_2} + 2{H_2}O \to Sr{\left( {OH} \right)_2} + 2HCl \cr
& BaC{l_2} + 2{H_2}O \to Ba{\left( {OH} \right)_2} + 2HCl \cr
& MgC{l_2} + 2{H_2}O \to Mg{\left( {OH} \right)_2} + 2HCl \cr
& CaC{l_2} + 2{H_2}O \to Ca{\left( {OH} \right)_2} + 2HCl \cr} $$
The basic nature of alkaline earth metals generally increases from $$Be$$ to $$Ra.$$ Thus, the order of basic nature of these hydroxides is $$Mg{\left( {OH} \right)_2} < Ca{\left( {OH} \right)_2} < Sr{\left( {OH} \right)_2} < Ba{\left( {OH} \right)_2}$$
Hence, $$pH$$ is highest for $$BaC{l_2}.$$ ( As $$pH$$ increases with basic nature )
173.
Among the given statements, the incorrect one is
A
Be differs much from other alkali metals than $$Li$$ does from other alkali metals.
B
$$Be$$ generally forms covalent compounds.
C
$$Be$$ forms a very strong complex, $${\left[ {Be{{\left( {{H_2}O} \right)}_4}} \right]^{2 + }}.$$
D
$$Be$$ usually has more than four water of crystallisation associated with it.
Answer :
$$Be$$ usually has more than four water of crystallisation associated with it.
174.
On reaction with dihydrogen the alkali metals
A
form hydrides which are ionic solids with high melting points
B
form hydrides which are molecular solids with low melting points
C
form hydrides which are ionic solids with low melting points
D
form hydrides which are non - stoichiometric.
Answer :
form hydrides which are ionic solids with high melting points
Alkali metals react with dihydrogen to form hydrides which are ionic solids with high melting points.
175.
Alkali metals cannot be extracted by reduction of their oxides and other compounds because
A
alkali metals are strong reducing agents
B
alkali metals have low ionisation enthalpy
C
alkali metals have high lattice enthalpy
D
alkali metals are strongly basic in nature
Answer :
alkali metals are strong reducing agents
No explanation is given for this question. Let's discuss the answer together.
176.
Baking soda is
A
$$NaHC{O_3}$$
B
$$NaHC{O_3} \cdot 6{H_2}O$$
C
$$N{a_2}C{O_3}$$
D
$$N{a_2}C{O_3} \cdot 10{H_2}O$$
Answer :
$$NaHC{O_3}$$
Sodium hydrogen carbonate, $$NaHC{O_3}$$ ( sodium bicarbonate ) is commonly called bicarbonate of soda or baking soda.
177.
One word answers are given for the following. Mark the example which is not correct.
A
Alkali metal with lowest melting point - $$Cs$$
B
Alkaline earth metal with highest hydration enthalpy - $$B{a^{2 + }}$$
C
Alkaline earth metal which imparts brick red colour to the flame - $$C{a^{2 + }}$$
D
Oxide of alkaline earth metal which is amphoteric in nature - $$BeO$$
Answer :
Alkaline earth metal with highest hydration enthalpy - $$B{a^{2 + }}$$
Hydration enthalpy decreases with increase in ionic size down the group.
$$B{e^{2 + }} > M{g^{2 + }} > C{a^{2 + }} > S{r^{2 + }} > B{a^{2 + }}$$
178.
Which of the following is not true about alkali metals?
A
Alkali metals do not occur free in nature.
B
Alkali metals are good oxidising agents.
C
Alkali metal salts impart colour to the flame.
D
Alkali metal salts are generally ionic.
Answer :
Alkali metals are good oxidising agents.
Alkali metals are good reducing agents.
179.
An element $$X$$ burns in nitrogen to give a compound $$Y$$ which on reaction with water gives a compound $$Z$$ and a gas with a pungent smell. $$Z$$ can be used during construction and white washing. When excess of $$C{O_2}$$ is bubbled through $$Z,$$ a compound $$P$$ is formed which on heating decomposes to give a colourless, odourless gas. Identify $$X, Y, Z$$ and $$P.$$
$$X$$
$$Y$$
$$Z$$
$$P$$
(a)
$$Ca$$
$$C{a_3}{N_2}$$
$$Ca{\left( {OH} \right)_2}$$
$$Ca{\left( {HC{O_3}} \right)_2}$$
(b)
$$Mg$$
$$MgO$$
$$Mg{\left( {OH} \right)_2}$$
$$MgC{O_3}$$
(c)
$$Ca$$
$$C{a_3}{N_2}$$
$$Ca{\left( {OH} \right)_2}$$
$$CaC{O_3}$$
(d)
$$Ca$$
$$CaO$$
$$Ca{\left( {OH} \right)_2}$$
$$Ca{\left( {HC{O_3}} \right)_2}$$
A
(a)
B
(b)
C
(c)
D
(d)
Answer :
(a)
$$\mathop {3Ca}\limits_{\left( X \right)} + {N_2} \to \mathop {C{a_3}{N_2}}\limits_{\left( Y \right)} $$
$$C{a_3}{N_2} + 6{H_2}O \to 3\mathop {Ca{{\left( {OH} \right)}_2}}\limits_{\left( Z \right)} + $$ $$\mathop {2N{H_3}}\limits_{\left( {{\text{gas with a pungent smell}}} \right)} $$
$$\mathop {Ca{{\left( {OH} \right)}_2}}\limits_{\left( Z \right)} + \mathop {C{O_2}}\limits_{{\text{excess}}} \to \mathop {Ca\left( {HC{O_3}} \right)}\limits_{\left( P \right)} $$
\[\underset{\left( P \right)}{\mathop{Ca{{\left( HC{{O}_{3}} \right)}_{2}}}}\,\xrightarrow{\text{heat}}CaC{{O}_{3}}+\] $${H_2}O + C{O_2}$$
180.
The decreasing order of the second ionization potential of $$Mg, Ca$$ and $$Ba$$ is
A
$$Mg > Ca > Ba$$
B
$$Ca > Ba > Mg$$
C
$$Ba > Mg > Ca$$
D
$$Mg > Ba > Ca$$
Answer :
$$Mg > Ca > Ba$$
Both Ist and 2nd ionization energies decreases down the group.