Learn Ionic Equilibrium MCQ questions & answers in Physical Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
1.
Which of the following salts is the most basic in aqueous solution?
A
$$Al{\left( {CN} \right)_3}$$
B
$$C{H_3}COOK$$
C
$$FeC{l_3}$$
D
$$Pb{\left( {C{H_3}COO} \right)_2}$$
Answer :
$$C{H_3}COOK$$
$${C{H_3}COOK}$$ is a salt of weak acid $$\left( {C{H_3}COOK} \right)$$ and strong base $$\left( {KOH} \right)$$
$$FeC{l_3}$$ is a salt of weak base $$\left[ {Fe{{\left( {OH} \right)}_3}} \right]$$ and strong acid $$\left( {HCl} \right)$$ .
$$Pb{\left( {C{H_3}COO} \right)_2}$$ is a salt of weak base $$Pb{\left( {OH} \right)_2}$$ and weak acid $$\left( {C{H_3}OOH} \right)$$
$$Al{\left( {CN} \right)_3}$$ is a salt of weak base $$\left[ {Al{{\left( {OH} \right)}_3}} \right]$$ and weak acid $$\left( {HCN} \right).$$
2.
The best indicator for detection of end point in titration of a weak acid and a strong base is :
A
methyl orange ( 3 to 4 )
B
methyl red ( 5 to 6 )
C
bromothymol blue ( 6 to 7.5 )
D
phenolphthalein ( 8 to 9.6 )
Answer :
phenolphthalein ( 8 to 9.6 )
TIPS/Formulae :
The pH of the solution at the equivalence point will be greater than 7 due to salt hydrolysis. So an indicator giving colour in basic medium will be suitable.
Phenolphthalein is a good indicator if the base is strong because strong base immediately changes the $$pH$$ at end point.
3.
Which is the strongest acid in the following?
A
$${H_2}S{O_4}$$
B
$$HCl{O_3}$$
C
$$HCl{O_4}$$
D
$${H_2}S{O_3}$$
Answer :
$$HCl{O_4}$$
The strength of oxyacids can also be decided with the help of the oxidation number of central atom. Higher the oxidation number of central atom, more acidic is the oxyacid.
$$\eqalign{
& \mathop {{H_2}S{O_4}}\limits^{ + 6} ,\mathop {HCl{O_3}}\limits^{ + 5} ,\mathop {HCl{O_4}}\limits^{ + 7} ,\mathop {{H_2}S{O_3}}\limits^{ + 4} \cr
& {\text{Order of acidic nature}} \cr
& HCl{O_4} > {H_2}S{O_4} > HCl{O_3} > {H_2}S{O_3} \cr} $$
Since, in $$HCl{O_4},$$ oxidation number of $$Cl$$ is highest, so, $$HCl{O_4}$$ is the strongest acid among the given acids.
4.
At $${25^ \circ }C,$$ the solubility product of $$Mg{\left( {OH} \right)_2}$$ is 1.0 × 10-11. At which $$pH,$$ will $$M{g^{2 + }}$$ ions start precipitating in the form of $$Mg{\left( {OH} \right)_2}$$ from a solution of $$0.001\,M\,M{g^{2 + }}$$ ions?
5.
Classify the following as acid or base according to Bronsted - Lowry concept.
$$\eqalign{
& \left( {\text{i}} \right)C{H_3}CO{O^ - } \cr
& \left( {{\text{ii}}} \right){H_3}{O^ + } \cr
& \left( {{\text{iii}}} \right)SO_4^{2 - } \cr
& \left( {{\text{iv}}} \right)HCl \cr} $$
(i)
(ii)
(iii)
(iv)
(a)
Bronsted base
Bronsted base
Bronsted base
Bronsted acid
(b)
Bronsted base
Bronsted acid
Bronsted acid
Bronsted base
(c)
Bronsted base
Bronsted acid
Bronsted base
Bronsted acid
(d)
Bronsted acid
Bronsted acid
Bronsted base
Bronsted base
A
(a)
B
(b)
C
(c)
D
(d)
Answer :
(c)
Any species which can accept a proton is Bronsted base while which can give a proton is Bronsted acid.
6.
The solubility product of $$AgCl$$ is $$1.8 \times {10^{ - 10}}.$$ Precipitation of $$AgCl$$ will occur by mixing which of the following solutions in equal volumes?
A
$${10^{ - 8}}\,M\,A{g^ + }\,\,{\text{and}}\,\,{10^{ - 8}}\,M\,C{l^ - }\,ions$$
B
$${10^{ - 3}}\,M\,A{g^ + }\,\,{\text{and}}\,\,{10^{ - 3}}\,M\,C{l^ - }\,ions$$
C
$${10^{ - 6}}\,M\,A{g^ + }\,\,{\text{and}}\,\,{10^{ - 6}}\,M\,C{l^{ - 1}}\,ions$$
D
$${10^{ - 10}}\,M\,A{g^ + }\,\,{\text{and}}\,\,{10^{ - 10}}\,M\,C{l^{ - 1}}\,ions$$
8.
Which of the following is conjugate acid of $$SO_4^{2 - }?$$
A
$$HSO_4^ - $$
B
$${H^ + }$$
C
$${H_2}S{O_4}$$
D
$$SO_4^{2 - }$$
Answer :
$$HSO_4^ - $$
Conjugate acid of $$SO_4^{2 - }$$ is $$HSO_4^ - .$$
9.
Amongst the following hydroxides, the one which has the
lowest value of $${K_{sp}}$$ at ordinary temperature ( about $${25^ \circ }C$$ ) is
A
$$Mg{\left( {OH} \right)_2}$$
B
$$Ca{\left( {OH} \right)_2}$$
C
$$Ba{\left( {OH} \right)_2}$$
D
$$Be{\left( {OH} \right)_2}$$
Answer :
$$Be{\left( {OH} \right)_2}$$
NOTE : In case of alkaline earth hydroxides solubility
increases on moving down the group.
$$Be{\left( {OH} \right)_2}$$ has lowest solubility and hence lowest
solubility product. [ $$Be$$ at tip of the group ]
10.
In which of the following the solubility of $$AgCl$$ will be minimum?
A
$$0.1\,M\,NaN{O_3}$$
B
$${\text{Water}}$$
C
$$0.1\,M\,NaCl$$
D
$$0.1\,M\,NaBr$$
Answer :
$$0.1\,M\,NaCl$$
In $$0.1\,M\,NaCl,$$ the solubility of $$AgCl$$ is minimum due to the phenomenon of common ion effect.