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CBSE Questions for Class 11 Medical Chemistry Equilibrium Quiz 14 - MCQExams.com
CBSE
Class 11 Medical Chemistry
Equilibrium
Quiz 14
At
90
∘
C
, pure water has
[
H
3
O
+
]
=
10
−
6.7
m
o
l
/
l
i
t
. What is the value of
K
W
at
90
∘
C
:
−
Report Question
0%
10
−
6
0%
10
−
12
0%
10
−
14
0%
10
−
13.4
Which of the following will not function as buffer solution?
Report Question
0%
Na
H
2
P
O
4
+ N
a
2
HP
O
4
(
1:1
Molar
Ratio
)
0%
N
H
4
Cl + NaOH
(
2:1
Molar
Ratio
)
0%
HCOOH + NaOH
(
1:1
Molar
Ratio
)
0%
HCOOH + HCOONa
(
1:1
Molar
Ratio
)
In which of the following solution of electrolyte, ionic equilibrium is set up?
Report Question
0%
H
2
S
O
4
0%
H
C
l
0%
N
a
O
H
0%
H
C
N
Which of the following is a buffer solution?
Report Question
0%
500 mL of 0.1 N CH
3
COOH +500 mL of 0.4 N NaOH
0%
500 mL of 0.1 N CH
3
COOH +500 mL of 0.1 N HCl
0%
500 mL of 0.1 N CH
3
COOH +500 mL of 0.2 N NaOH
0%
500 mL of 0.1 N CH
3
COOH +500 mL of 0.3N NaOH
On adding NaCl solution to the saturated solution of
P
b
C
l
2
then the concentration of :
Report Question
0%
P
b
2
+
will increase
0%
C
l
−
will decrease
0%
P
b
2
+
will decrease
0%
Ions will remain unaltered
The ionic product of water at
25
o
C
is
10
−
14
The ionic product at
90
o
C
will be
Report Question
0%
1
×
10
−
20
0%
1
×
10
−
12
0%
1
×
10
−
14
0%
1
×
10
−
16
In a buffer solution the ratio of concentration of
N
H
4
Cl
and
N
H
4
OH
is
1:1
when it changes in 2:1 what will be the value of pH of buffer:-
Report Question
0%
Increase
0%
Decrease
0%
No effects
0%
N. O. T.
A hydrogen electrode placed in a buffer solution of NaCl and HCN in the ratio of X:Y and Y:X has an oxidation electrode potential values
E
1
a
n
d
E
2
volts respectively at
25
0
C
. The pKa value of HCN is
Report Question
0%
(
E
1
+
E
2
)
0.118
0%
−
(
E
1
+
E
2
)
0.118
0%
(
E
1
−
E
2
)
0.118
0%
(
E
2
−
E
1
)
0.118
If the degree of ionization of water is 1.8 x
10
−
9
at a given temperature. Its ionic product will be
Report Question
0%
1.8 x
10
−
16
0%
1 x
10
−
14
0%
1 x
10
−
16
0%
1.67 x
10
−
14
2
H
2
O
⇋
H
3
O
+
+
O
H
−
,
K
w
=
1
×
10
−
14
at
25
∘
C
hence
K
a
is :
Report Question
0%
1
×
10
−
14
0%
18
×
10
−
17
0%
5.55
×
10
−
3
0%
1.00
×
10
−
7
The dissociation constant of a weak acid is
1.0
×
10
−
5
, the equilibrium constant for its reaction with strong base is
Report Question
0%
1.0
×
10
−
5
0%
1.0
×
10
9
0%
1.0
×
10
7
0%
1.0
×
10
14
One litre of water contains
10
−
7
mole of
H
+
ions. Degree of ionisation of water is:
Report Question
0%
1.8
×
10
−
7
%
0%
0.8
×
10
−
9
%
0%
3.6
×
10
−
9
%
0%
3.6
×
10
−
7
%
Explanation
1
litre of water contains
1000
/
18
mole.
So degree of ionization
=
10
−
7
×
18
1000
=
1.8
×
10
−
7
%
Option A is correct.
Aqueous solution of NaCl is neutral because
Report Question
0%
N
a
+
undergoes hydrolysis
0%
Cl undergoes hydrolysis
0%
Both
N
a
+
and Cl undergo hydrolusis
0%
Does not undergo hydrolysis
Which of the following may be regarded as buffer solution?
Report Question
0%
50 ml of 0.1 M acetic acid + 50 ml of 0.05 M
N
a
O
H
0%
50 ml of 0.05 ammonia + 50 ml of 0.1 M
H
C
l
0%
25 ml of 0.1 M acetic acid + 50 ml of 0.1 M
N
a
O
H
0%
50 ml of 0.1 ammonia + 50 ml of 0.05 M
H
C
l
The total number of different kind of buffer obtained during the titration of
H
3
P
O
4
with NaOH are:-
Report Question
0%
3
0%
1
0%
2
0%
0
Select the correct acid-base equilibrium.
Report Question
0%
H
N
O
3
+
H
F
⇌
H
2
N
O
+
3
+
F
−
0%
H
N
O
3
+
H
F
⇌
H
2
F
+
+
N
O
−
3
0%
C
H
3
C
O
O
H
+
N
H
3
⇌
C
H
3
C
O
O
H
+
2
+
N
H
+
2
0%
H
F
+
H
2
O
⇌
H
2
F
+
+
O
H
−
H
C
O
O
H
and
C
H
3
C
O
O
H
solutions have equal
p
H
. If
K
1
K
2
(ratio of ionisation constants of acids) is 4, their molar concentration ratio will be:
Report Question
0%
2
0%
0.5
0%
4
0%
0.25
At
90
∘
C
,
pure water has
[
H
3
O
+
]
=
10
−
6
m
o
l
litre
−
1
.
The value of
K
w
at
90
∘
C
is:
Report Question
0%
10
−
6
0%
10
−
12
0%
10
−
14
0%
10
−
8
Hydrogen ion concentration of an aqueous solution is
1
×
10
−
4
M
. The solution is diluted with equal volume of water. Hydroxyl ion concentration of the resultant solution in terms of mol
d
m
−
3
is __________.
Report Question
0%
1
×
10
−
8
0%
1
×
10
−
6
0%
2
×
10
−
10
0%
0.5
×
10
−
10
Explanation
Concentration of aqueous solution=
10
−
4
M
If we add equal volume, let say V of water. The final volume of solution will be 2V. The new concentration is
⇒M_1V_1=M_2V_2
⇒10^{−4}M×V=M_2×2V
⇒M_2=5×10−5M ⟶ \text{New concentration of }[H^+] .
pH=−log[H^+]=−log[5×10^{−5}]
⇒pH=4.3
⇒pOH=14−pH=9.69
⇒−log[OH^-]=9.69
⇒[OH^-]=10^{−9.69}=2×10^{−10}
\text{Thus the concentration of }[OH^-] \ is\ 2×10^{−10}M .
If
1M
C{H_3}COONa
is added to
1M
C{H_3}COOH
, then:
Report Question
0%
pH
of the solution increases
0%
pH
decreases
0%
pH
does not change
0%
cannot be predicted
The dissociation constants for acetic acid and HCN at
25^{0}
C are
1 . 5 \times 10^{-5}
and
4 . 5 \times 10 ^{-10}
, respectively. The equilibrium constant for the equilibrium
CN^{-} + CH_{3}COOH \leftrightharpoons HCN + CH_{3}COO^{-}
would be :
Report Question
0%
3\times10^{4}
0%
3\times10^{5}
0%
3\times10^{-5}
0%
3\times10^{-4}
At
{ 25 }^{ \circ }C
the dissociation constant of a base , BOH, is
1.0\times { 10 }^{ -12 }
. The concentration of hydroxyl ions in 0.01 M aqueous solution of the base would be
Report Question
0%
1.0\times { 10 }^{ -6 }{ molL }^{ -1 }
0%
1.0\times { 10 }^{ -7 }{ molL }^{ -1 }
0%
2.0\times { 10 }^{ -6 }{ molL }^{ -1 }
0%
1.0\times { 10 }^{ -5 }{ molL }^{ -1 }
A solution is saturated with respect to
AgSCN
as well as
AgBr
. The concentration of
Ag^{+}
in the solution would be:
(
K_{sp}
for
AgSCN = 1.2 \times 10^{-12}
and for
AgBr = 5 \times 10^{-13}
)
Report Question
0%
1.3 \times 10^{-5}
0%
1.3 \times 10^{-12}
0%
1.3 \times 10^{-6}
0%
1.3 \times 10^{-8}
Which of the following salt evolve(s)
{ N }_{ 2 }
gas on heating ?
Report Question
0%
\left( { NH }_{ 4 } \right) _{ { 2 } }{ CrO }_{ 4 }
0%
{ NH }_{ 4 }{ NO }_{ 2 }
0%
{ NH }_{ 4 }{ NO }_{ 3 }
0%
\left( { NH }_{ 4 } \right) _{ { 2 } }{ CO }_{ 3 }
Which of following salt solution will impart greenish colour ?
Report Question
0%
K_2Cr_2O_7
0%
ZnCl_2
0%
K_2MnO_4
0%
K_2CrO_4
10 ml of 0.2 M
AgNO_3
is mixed with 10 ml of 0.1 M
NaCl
. What is the concenctration of
Cl^-
in the resulting solution
[ K_{sp} (AgCl) = 10^{-10} M^2]
Report Question
0%
10^{-5} M
0%
10^{-9} M
0%
2 \times 10^{-9} M
0%
10^{-8} M
For preparing a buffer solution of pH = 7.0, which buffer system you will choose?
Report Question
0%
H_3PO_4,H_2PO_4^-
0%
H_2PO_4^-, HPO_4^{2-}
0%
HPO^{2-}_4, PO^{3-}_4
0%
H_3PO_4, PO_4^{3-}
The percentage of pyridine
\left( { C }_{ 5 }{ H }_{ 5 }N \right)
that forms pyridinium ion
\left( { C }_{ 5 }{ H }_{ 5 }{ N }^{ + }H \right)
in a 0.10 m aqueous pyridine solution
\left( K_{ b } \ for\ { C }_{ 5 }{ H }_{ 5 }N=1.7\times { 10 }^{ -9 } \right)
is:
Report Question
0%
0.0060%
0%
0.013%
0%
0.77%
0%
1.6%
A weak acid react with strong base, ionisation constant of weak acid is
{ 10 }^{ -4 }
. Find out equilibrium constant for this reaction.
Report Question
0%
{ 10 }^{ -10 }
0%
{ 10 }^{ 10 }
0%
{ 10 }^{ -9}
0%
{ 10 }^{ 9}
Which statement is/are correct-
Report Question
0%
If
0.1\ M
CH_3COOH
aqueous solution
( K_a = 1.8 \times 10^{-5} )
is diluted at
2560^o C
, then
[H^+]
will increase
0%
On heating a sample of pure water
[H^+]
and
[OH^-]
increases but the sample still remains neutral
0%
10^{-4}\ M
HCl
solution is less acidic than
0.1\ M
HCN
( K_a HCN = 10^{-5} )
0%
10^{-8}\ M
HCl
aqueous solution will have pH exactly equal to 8
The self ionisation constant of
\mathrm { NH } _ { 3 }
at
50 ^ { \circ } \mathrm { C }
is given by
\mathrm { K } _ { \mathrm { NH } _ { 3 } } = \left[ \mathrm { NH } _ { 4 } ^ { + } \right] \left[ \mathrm { NH } _ { 2 } ^ { - } \right] = 10 ^ { - 30 }
. How many
N H _ { 2 } ^ { - }
ions are present per
\mathrm { cm } ^ { 3 }
of pure liquid
\mathrm { NH } _ { 3 }
?
Report Question
0%
6 \times 10 ^ { 6 }
0%
6 \times 10 ^ { 5 }
0%
6 \times 10 ^ { - 5 }
0%
6 \times 10 ^ { - 6 }
The dissociation constant of an acid HA is
1 \times 10 ^ { - 5 }
. The pH of 0.1 molar solution of the acid will be approximately:
Report Question
0%
3
0%
5
0%
1
0%
6
The silicate anion in the mineral kinetic is a chain of three
SiO_4^{4^-}
tetrahedral that shares conners with adjacent tetrahedral. The mineral also contains
Ca
icon
Cu
ions and water molecules in a 1:1:1 ratio mineral represented as:
Report Question
0%
CaCu_2Si_{ 3 }O_{ 10 }.H_{ 2 }O
0%
CaCuSi_{ 3 }O_{ 10 }.H_{ 2 }O
0%
Ca_{ 2 }Cu_{ 2 }Si_{ 3 }O_{ 10 }.2H_{ 2 }O
0%
None of these
Which of the following is ionic?
Report Question
0%
HCl
0%
CHCl_3
0%
IF_5
0%
KI
For which salt the
\mathrm { pH }
of its solution does not change with dilution?
Report Question
0%
\mathrm { NH } _ { 4 } \mathrm { Cl }
0%
\mathrm { CH } _ { 3 } \mathrm { COONH } _ { 4 }
0%
\mathrm { CH } _ { 3 } \mathrm { COONa }
0%
None of these
Consider the following equilibrium.
Liquid
\rightleftharpoons
Vapour
Which of the following relation is correct?
Report Question
0%
\dfrac{d ln P}{dT}=\dfrac{\Delta Hv}{RT^2}
0%
\dfrac{d ln G}{dT^2}=\dfrac{\Delta Hv}{RT^2}
0%
\dfrac{d ln P}{dT}=\dfrac{-\Delta Hv}{RT}
0%
\dfrac{d ln P}{dT^2}=\dfrac{-\Delta Hv}{T^2}
The
pH
of an aqueous solution of sodium chloride at
60^{\circ}C
is
Report Question
0%
7.0
0%
> 7.0
0%
<7.0
0%
0
Explanation
We know that at
25^{\circ}C
dissociation constant
K_w
of water is,
H_2O\rightleftharpoons H^++OH^-
[H^+][OH^-]=10^{-14}=K_w
So,
[H^+]=[OH^-]=10^{-7}M
Thus
pH=7
for
H_2O
at
25^{\circ}C
Adding
NaCl
does not affect the
pH
whatever be the temperature because sodium chloride is salt of strong acid and strong base. So, it is
H^+
ion of water which is affecting the
pH
.
Dissociation of water is an endothermic process. With an increase in
temperature
dissociation
constant of water increases. So the dissociation constant is more i.e.,
K_w>10^{-14}
.
Therefore,
[H^+]>10^{-7}
and
pH
is less than 7.
Hence the correct option is (C).
The EMF of cell:
H_{2}(g)|
Buffer
\parallel
Normal calmelelectrod, is 0.70 V at
25^{\circ}C,
when barometric pressure is 760 mm. What is the pH of the buffer solution?
E_{Calomel}^{0} = 0.28 V. [2.303 RTIF = 0.06]
Report Question
0%
3.5
0%
7.0
0%
tending to zero
0%
tending to 14.0
The dissociation constant of formic acid is
0.00024
. The hydrogen ion concentration in
0.002 M \ HCOOH
solution is nearly
Report Question
0%
6.93 \times 10^{-4}M
0%
4.8 \times 10^{-7}M
0%
5.8 \times 10^{-4}M
0%
1.4 \times 10^{-4}M
The degree of dissociation of pure water at
25^{\circ}C
is found to be
1.8 \times 10^{-9}
. The dissociation constant,
K_{d}
of water, at
25^{\circ}C
is
Report Question
0%
10^{-14}
0%
1.8 \times 10^{-16}
0%
5.56 \times 10^{-13}
0%
1.8 \times 10^{-14}
Explanation
Given:
Degree of dissociation of pure water,
\alpha =1.8\times 10^{-9}
We know that,
Density of pure water =
1\space g\space cm^{-3}=1000\space g\space L^{-1}
Molar mass of water =
18\space g\space mol^{-1}
Concentration=\frac{number\space of\space moles}{Volume}=\frac{1000\space g\space L^{-1}}{18\space g\space mol^{-1}}=55.5\space M
Dissociation of water,
H_2O\rightleftharpoons H^++OH^-
Dissociation constant,
K_d=\frac{[H^+][OH^-]}{[H_2O]}=\frac{C\alpha\times C\alpha}{C-C\alpha}
As
\alpha<<<1
,
[H_2O]
is not affected.
Therefore,
K_d=c\alpha^2=55.5\times (1.8\times 10^{-9})^2=1.79\times 10^{-16}\approx 1.8\times 10^{-16}
Hence, the correct option is (B).
Which one of the following salts gives aqueous solution which is neutral?
Report Question
0%
NaHC{ O }_{ 3 }
0%
NaHS{ O }_{ 4 }
0%
NaCl
0%
\\ Na{ H }_{ 4 }HC{ O }_{ 3 }
When ammonia is added to pure water, the concentration of which of the following species already present, will decrease?
Report Question
0%
OH^-
0%
H_3O^+
0%
NH_4^+
0%
None of these
n-caproic acid,
C_{5}H_{11}COOH
, found in coconut and palm oil is used in making artificial flavors, has solubility in water equal to
11.6 g/L
. The saturated solution has
pH = 3.0
. The
K_{a }
of acid is
Report Question
0%
10^{-6}
0%
10^{-5}
0%
2 \times 10^{-5}
0%
2 \times 10^{-6}
What is
[H^+]
in mol/L of a solution that is 0.20 M
CH_3CCONa
and 0.10 M in
CH_3COOH
?
( K_a\ for\ CH_3COOH = 1.8 \times 10^{-5} )
Report Question
0%
3.5 \times 10^{-4}
0%
1.1 \times 10^{-5}
0%
1.8 \times 10^{-5}
0%
9.0 \times 10^{-6}
A solution has initially
0.1 M -HCOOH
and
0.2 M- HCN
.
K_{a}
of
HCOOH = 2.56 \times 10^{-4}
,
K_{a}
of
HCN = 9.6 \times 10^{-10}
. The only incorrect statement for the solution is
(log 2 = 0.3)
Report Question
0%
[H]^{+} = 1.6 \times 10^{-3} M
0%
[HCOO]^{-} = 1.6 \times 10^{-3} M
0%
[CN]^{-} = 1.2 \times 10^{-7} M
0%
pOH = 2.8
Calculate the formation constant for the reaction of a tripositive metal ion with thiocyanate ions to form the monocomplex if the total metal concentration in the solution is
2 \times 10^{-3} M
, the total
SCN^{-}
concentration is
1.51 \times 10^{-3} M
and the free
SCN^{-}
concentration is
1.0 \times 10^{-5} M
.
Report Question
0%
7.55 \times 10^{4}
0%
3 \times 10^{5}
0%
3.33 \times 10^{-6}
0%
1.5 \times 10^{5}
Small amount of freshly precipitated magnesium hydroxides are stirred vigorously in a buffer solution containing
0.25 M
of
NH_{4}Cl
and
0.05 M
of
NH_{4}OH
.
[Mg^{2+}]
in the resulting solution is (
K_{b}
for
NH_{4}OH = 2.0 \times 10^{-5}
and
K_{sp}
of
Mg(OH)_{2} = 8.0 \times 10^{-12}
)
Report Question
0%
4 \times 10^{-6} M
0%
2 \times 10^{-6} M
0%
0.5 M
0%
2.0 M
A volume of
1.0 L
of solution which was in equilibrium with solid mixture of
AgCl
and
Ag_{2}CrO_{4}
was found to contain
1 \times 10^{-4}
moles of
Ag^{+}
ions,
1.0 \times 10^{-6}
moles of
CI^{-}
ions and
8.0 \times 10^{-4}
moles of
CrO_{4}^{2-}
ions.
Ag^{+}
ions are added slowly to the above mixture (keeping the volume constant) till
8.0 \times 10^{-7}
moles of
AgCl
got precipitated. How many moles of
Ag_{2}CrO_{4}
were precipitated simultaneously?
Report Question
0%
7.68 \times 10^{-4}
0%
4.8 \times 10^{-4}
0%
8.0 \times 10^{-4}
0%
7.68 \times 10^{-5}
Which one of the following is not an acid salt?
Report Question
0%
NaH_2PO_2
0%
NaH_2PO_3
0%
NaH_2PO_4
0%
Na_2HPO_4
Explanation
NaH_2PO_2
is not an acidic salt. It is a basic salt. It is a salt of weak acid
H_3PO_2
and a strong base
NaOH
. Hence, the aqueous solution of
NaH_2PO_2
is alkaline in nature. In
NaH_2PO_2,
there is no acidic hydrogen.
Hence, the correct option is (A).
The solubility of
AgCN
in a buffer solution of
pH - 3.0
is (
K_{sp}
of
AgCN = 1.2 \times 10^{-16}
;
K_{a}
of
HCN = 4.8 \times 10^{-10}
)
Report Question
0%
1.58 \times 10^{-5}M
0%
2.0 \times 10^{-5}M
0%
1.58 \times 10^{-4}M
0%
2.5 \times 10^{-9}M
Explanation
Assume solubility of AgCN be a M in presence of a buffer of pH = 3
Given :-
K_{sp}
of AgCN =
1.2 \times 10^{-16}
and
K_{a}
for HCN =
4.8 \times 10^{-10}
AgCN \rightleftharpoons Ag^{+} + CN^{-}
[Ag^{+}] = a; \quad [H^+] = 10^-{3}M;
For weak HCN,
K_{a} = \frac{[H^{+}][CN^{-}]}{[HCN]}
\Rightarrow 4.8 \times 10^{-10} = \dfrac{[10^{-3}][CN^{-}]}{a}
\therefore [CN^{-}] = 4.8 \times 10^{-7} \times a
For \ AgCN : K_{sp} = Ag^{+} \times CN^{-}
1.2 \times 10^{-16} = a \times 4.8 \times 10^{-7} \times a
a^{2} = \dfrac{1.2 \times 10^{-16}}{4.8 \times 10^{-7}}
a = 1.58 \times 10^{-5} M
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Practice Class 11 Medical Chemistry Quiz Questions and Answers
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