S - Block Elements MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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231.
A substance absorbs $$C{O_2}$$ and voilently reacts with water. The substance is
On heating with excess of air $$Li,Na$$ and $$K$$ forms following oxides
\[\begin{align}
& 4Li+{{O}_{2}}\to \underset{\text{Lithium monoxide }}{\mathop{2L{{i}_{2}}O}}\, \\
& 2Na+{{O}_{2}}\xrightarrow{575\,K}\underset{\text{Sodium peroxide }}{\mathop{N{{a}_{2}}{{O}_{2}}}}\, \\
& K+{{O}_{2}}\to \underset{\text{Potassium superoxide}}{\mathop{K{{O}_{2}}}}\, \\
\end{align}\]
238.
Which of the following will have lowest value of $${K_{sp}}$$ at room temperature?
A
$$Be{\left( {OH} \right)_2}$$
B
$$Mg{\left( {OH} \right)_2}$$
C
$$Ca{\left( {OH} \right)_2}$$
D
$$Ba{\left( {OH} \right)_2}$$
Answer :
$$Be{\left( {OH} \right)_2}$$
$$Be{\left( {OH} \right)_2}$$ is least soluble in water hence, it will have lowest value of $${K_{sp}}.$$
$$Be{\left( {OH} \right)_2} \rightleftharpoons B{e^{2 + }} + 2O{H^ - };$$ $${K_{sp}} = \left[ {B{e^{2 + }}} \right]{\left[ {O{H^ - }} \right]^2}$$
239.
Some of the group 2 metal halides are covalent and soluble in organic solvents. Among the following metal halides, the one which is soluble in ethanol is
A
$$BeC{l_2}$$
B
$$MgC{l_2}$$
C
$$CaC{l_2}$$
D
$$SrC{l_2}$$
Answer :
$$BeC{l_2}$$
Beryllium halides are essentially covalent and soluble in organic solvents like ethanol.
240.
Match column I with column II and mark the appropriate choice.
Column I
Column II
a.
$$Li$$
1.
$${M_2}{O_2}$$
b.
$$Na$$
2.
$$M{O_2}$$
c.
$$Rb$$
3.
$${M_2}O$$
A
a - 1, b - 2, c - 3
B
a - 3, b - 2, c - 1
C
a - 3, b - 1, c - 2
D
a - 2, b - 3, c - 1
Answer :
a - 3, b - 1, c - 2
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