Chemistry-Question-Bank-píginas-14

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118 EQUILIBRIUM
108. What is [H+] in mol/L of a solution that is 0.20 M in
CH3COONa and 0.10 M in CH3COOH ? Ka for CH3COOH
= 1.8 × 10–5.
(a) 3.5 × 410 (b) 1.1 × 510
(c) 1.8 × 510 (d) 9.0 × 610
109. Which of the following pairs constitutes a buffer?
(a) NaOH and NaCl (b) HNO3 and NH4NO3
(c) HCl and KCl (d) HNO2 and NaNO2
110. Buffer solutions have constant acidity and alkalinity
because
(a) these give unionised acid or base on reaction with
added acid or alkali.
(b) acids and alkalies in these solutions are shielded from
attack by other ions.
(c) they have large excess of H+ or OH– ions
(d) they have fixed value of pH
111. The buffering action of an acidic buffer is maximum when
its pH is equal
(a) 5 (b) 7
(c) 1 (d) pKa
112. When a buffer solution, sodium acetate and acetic acid is
diluted with water :
(a) Acetate ion concentration increases
(b) H+ ion concentration increases
(c) OH– ion conc. increases
(d) H+ ion concentration remains unaltered
113. The product of ionic concentration in a saturated solution
of an electrolyte at a given temperature is constant and is
known as
(a) Ionic product of the electrolyte
(b) Solubility product
(c) Ionization constant
(d) Dissociation constant
114. The Ksp for Cr(OH)3 is 1.6 × 10–30. The solubility of this
compound in water is :
(a) 4 301.6 10 (b) 4 301.6 10 / 27
(c) 30/ 271.6 10 (d) 301.6 10
115. At 25°C, the solubility product of Mg(OH)2 is 1.0 × 10–11.
At which pH, will Mg2+ ions start precipitating in the form
of Mg(OH)2 from a solution of 0.001 M Mg2+ ions?
(a) 9 (b) 10
(c) 11 (d) 8
116. pH of a saturated solution of Ba(OH)2 is 12. The value of
solubility product (Ksp) of Ba(OH)2 is :
(a) 3.3 × 10– 7 (b) 5.0 × 10–7
(c) 4.0 × 10–6 (d) 5.0 × 10–6
117. If s and S are respectively solubility and solubility product
of a sparingly soluble binary electrolyte then :
(a) s = S (b) s = S2
(c) 1/ 2s S (d) 1s S
2
118. Why only As+3 gets precipitated as As2S3 and not Zn+2 as
ZnS when H2S is passed through an acidic solution
containing As+3 and Zn+2?
(a) Solubility product of As2S3 is less than that of ZnS
(b) Enough As+3 are present in acidic medium
(c) Zinc salt does not ionise in acidic medium
(d) Solubility product changes in presence of an acid
119. Solid Ba(NO3)2 is gradually dissolved in a
1.0 × 10–4 M Na2CO3 solution. At which concentration of
Ba2+, precipitate of BaCO3 begins to form ? (Ksp for BaCO3
= 5.1 × 10–9)
(a) 5.1 × 10–5 M (b) 7.1 × 10–8 M
(c) 4.1 × 10–5 M (d) 8.1 × 1–7 M
120. Solubility product of silver bromide is 5.0 × 10–13. The
quantity of potassium bromide (molar mass taken as
120 g mol–1) to be added to 1 litre of 0.05 M solution of
silver nitrate to start the precipitation of AgBr is
(a) 1.2 × 10–10 g (b) 1.2 × 10–9 g
(c) 6.2 × 10–5 g (d) 5.0 × 10–8 g
121. At 25°C, the solubility product of Mg(OH)2 is
1.0 × 10–11. At which pH, will Mg2+ ions start precipitating
in the form of Mg(OH)2 from a solution of
0.001 M Mg2+ ions?
(a) 9 (b) 10
(c) 11 (d) 8
STATEMENT TYPE QUESTIONS
122. Read the following statements carefully and choose the
correct answer
(i) Water and water vapour remain in equilibrium position
at atmospheric pressure (1.013 bar) and at 100°C in a
closed vessel.
(ii) The boiling point of water is 100°C at 1.013 bar pressure
(iii) Boiling point of the liquid depends on the atmospheric
pressure.
(iv) Boiling point depends on the altitude of the place; at
high altitude the boiling point increases.
(a) (i), (ii) and (iv) are correct
(b) (i), (iii) and (iv)
(c) (i), (ii) and (iii) are correct
(d) only (iii) is correct
123. You must have seen that when a soda water bottle is opened,
some of the carbon dioxide gas dissolved in it fizzes out
rapidly. There is equilibrium between the molecules in the
gaseous state and the molecules dissolved in the liquid
under pressure i.e.,
 CO2(gas) CO2(in solution)
Which of the following statements is/are correct regarding
this?
(i) The phenomenon arises due to difference in solubility
of carbon dioxide at different pressures.
(ii) This equilibrium is governed by Henry's law.
(iii) The amount of CO2 gas dissolved in liquid increases
with decrease of temperature.
(iv) The amount of CO2 gas dissolved in liquid decreases
with increase of temperature.
(a) (i), (ii) and (iv) are correct
(b) (i) , (iii) and (iv)
(c) (i), (ii) and (iii) are correct
(d) only (iii) is correct
EQUILIBRIUM 119
124. Identify the CORRECT statements below regarding chemical
equilibrium:
(i) All chemical reactions which are in equilibrium are
irreversible.
(ii) Equilibrium is achieved when the forward reaction rate
equals the reverse reaction rate.
(iii) Equilibrium is achieved when the concentrations of
reactants and product remain constant.
(iv) Equilibrium is dynamic in nature
(a) (i), (ii) and (iv) are correct
(b) (i), (ii), (iii) and (iv) are correct
(c) (i), (ii) and (iii) are correct
(d) only (ii) is correct
125. Nobel gas is added to a reaction at equilibrium involving
gaseous reactant and gaseous product.
Which of the following statement is true for above reaction?
Statement 1 : Reaction will proceed forward, as total
pressure has increased due to addition of Nobel gas.
Statement 2 : Reaction will proceed backward, if Nobel gas
react with reactant.
(a) Statement 1 and 2 are both correct.
(b) Statement 1 is correct but statement 2 is incorrect.
(c) Statement 1 is incorrect but statement 2 is correct.
(d) Statement 1 and 2 both are incorrect.
126 Read the following statements and choose the correct
option.
(i) The value of equilibrium constant is independent of
initial concentrations of the reactants and products.
(ii) Equilibrium constant is temperature dependent
(iii) The equilibrium constant for the reverse reaction is
equal to the inverse of the equilibrium constant for the
forward reaction.
(iv) The equilibrium constant for the reverse reaction is
equal to the equilibrium constant for the forward
reaction.
(a) (i), (ii) and (iv) are correct
(b) (i), (iii) and (iv)
(c) (i), (ii) and (iii) are correct
(d) only (iii) is correct
127. Read the following statements and choose the correct option
(i) The numerical value of the equilibrium constant for a
reaction indicates the extent of the reaction.
(ii) An equilibrium constant give information about the
rate at which the equilibrium is reached.
(iii) If Kc > 103, products predominate over reactants, i.e.,
if Kc is very large, the reaction proceeds nearly to
completion.
(iv) If KcOnly (ii)
132. Which of the following statements are correct ?
(i) Ionic product of water (Kw) = [H+] [OH–] = 10–14M2
(ii) At 298K [H+] = [OH–] = 10–7
(iii) Kw does not depends upon temperature
(iv) Molarity of pure water = 55.55M
(a) (i), (ii) and (iii) (b) (i), (ii) and (iv)
(c) (i) and (iv) (d) (ii) and (iii)
133. Read the following statements and choose the correct option
(i) Ka (ionization constant) is a measure of the strength
of the acids
(ii) Smaller the value of Ka, the stronger is the acid
(iii) Ka is a dimensionless quantity
(a) Statements (i) and (ii) are correct
(b) Statements (ii) and (iii) are correct
(c) Statements (i), (ii) and (iii) are correct
(d) Statements (i) and (iii) are correct
134. Which of the following statement(s) is/are correct ?
(i) In a tribasic acid 2nd and 3rd (Ka2
, Ka3
) ionization
constants are smaller than the first ionisation (Ka1
)
(ii) It is difficult to remove a positively charged proton
from a negative ion due to electrostatic force.
(a) Both (i) and (ii) (b) Neither (i) nor (ii)
(c) Only (i) (d) Only (ii)
120 EQUILIBRIUM
135. Which of the following statements are correct ?
(i) The extent of dissociation of an acid depends on the
strength and polarity of the H –– A bond (where A is
an electronegative element.)
(ii) As the strength of H–A bond increases, the energy
required to break the bond decreases.
(iii) As the electronegativity difference between the atoms
H and A increases, acidity increases
(a) (i) and (ii) (b) (ii) and (iii)
(c) (i) and (iii) (d) (i), (ii) and (iii)
MATCHING TYPE QUESTIONS
136. Match the columns
Column-I Column-II
(A) H2O (l) H2O (vap) (p) rate of melting = rate of
freezing
(B) I2 (solid) (q) rate of evaporation
 I2 (vapour) = rate of condensation
(C) Ice water (r) rate of sublimation= rate
of condensation
(a) A – (p), B – (q), C – (r)
(b) A – (r), B – (q), C – (p)
(c) A – (p), B – (r), C – (q)
(d) A – (q), B – (r), C – (p)
137. Match the Column-I with Column-II and mark the appropriate
choice.
Column-I Column-II
(A) Liquid Vapour (p) Saturated solution
(B) Solid Liquid (q) Boiling point
(C) Solid Vapour (r) Sublimation point
(D) Solute (s) Solute (s) Melting point
 (solution)
(a) A – (p) ; B – (r) ; C – (q) ; D – (s)
(b) A – (q) ; B – (s) ; C – (r) ; D – (p)
(c) A – (s) ; B – (q) ; C – (p) ; D – (r)
(d) A – (r) ; B – (s) ; C – (q) ; D – (p)
138. Match the columns.
 Column-I Column-II
(Reactions) (Effect of increase in
 pressure)
(A) H2(g) + I2(g) 2HI(g) (p) Reaction proceed
backward.
(B) CO(g) + 
1
2
O2(g) (q) No effect on
CO2(g) reaction.
(C) N2O4(g) 2NO2(g) (r) Reaction proceed
forward
(a) A – (q), B – (r), C – (p)
(b) A – (r), B – (q), C – (p)
(c) A – (p), B – (r), C – (q)
(d) A – (q), B – (p), C – (r)
139. Match the columns :
Column-I Column-II
(A) N2(g) + 3H2(g) (p) n > 0
 2NH3(g) (t = 300ºC)
(B) PCl5(g) PCl3(g) (q) KP Kc, (q) Net reaction goes from
left to right.
(C) Qc = Kc, (r) No net reaction occurs.
(a) A – (p), B – (q), C – (r)
(b) A – (r), B – (q), C – (p)
(c) A – (p), B – (r), C – (q)
(d) A – (q), B – (p), C – (r)
EQUILIBRIUM 121
142. Match the columns
Column-I Column-II
(A) Hydrochloric acid (p) Lemon and orange
(B) Acetic acid (q) Tamarind paste.
(C) Citric and ascorbic (r) Digestive juice
acids
(D) Tartaric acid (s) Constituent of
vinegar
(a) A – (q), B – (r), C – (p), D – (s)
(b) A – (r), B – (s), C – (p), D – (q)
(c) A – (s), B – (p), C – (q), D – (r)
(d) A – (r), B – (p), C – (s), D – (q)
143. Match the columns
Column-I Column-II
(A) HClO4 (p) Strong base
(B) HNO2 (q) Strong acid
(C) NH2
– (r) Weak base
(D) HSO4
– (s) Weak acid
(a) A – (s), B – (q), C – (p), D – (r)
(b) A – (q), B – (s), C – (p), D – (r)
(c) A – (r), B – (p), C – (q), D – (s)
(d) A – (s), B – (q), C – (p), D – (r)
ASSERTION-REASON TYPE QUESTIONS
Directions : Each of these questions contain two statements,
Assertion and Reason. Each of these questions also has four
alternative choices, only one of which is the correct answer. You
have to select one of the codes (a), (b), (c) and (d) given below.
(a) Assertion is correct, reason is correct; reason is a correct
explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a
correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
144. Assertion : Kp can be less than, greater than or equal to Kc.
Reason : Relation between Kp and Kc depends on the
change in number of moles of gaseous reactants and
products ( n).
145. Assertion : If a volume is kept constant and an inert gas
such as argon is added which does not take part in the
reaction, the equilibrium remains undisturbed.
Reason : It is because the addition of an inert gas at constant
volume does not change the partial pressure or the molar
concentrations of the substance involved in the reaction.
146. Assertion : Buffer system of carbonic acid and sodium
bicarbonate is used for the precipitation of hydroxides of
third group elements.
Reason : It maintains the pH to a constant value, about 7.4.
147. Assertion : Addition of silver ions to a mixture of aqueous
sodium chloride and sodium bromide solution will first
precipitate AgBr rather than AgCl.
Reason : Ksp of AgCl > Ksp of AgBr.
CRITICAL THINKING TYPE QUESTIONS
148. N2(g) + 3H2(g) 2NH3(g), K1 (1)
N2(g) + O2(g) 2NO(g), K2 (2)
H2(g) + 
1
2
O2(g) H2O(g), K3 (3)
The equation for the equilibrium constant of the reaction
2NH3(g) + 2
5 O (g)
2
2NO(g) + 3H2O(g), (K4) in terms
of K1, K2 and K3 is :
(a)
1 2
3
K .K
K (b)
2
1 3
2
K .K
K
(c) K1 K2 K3 (d)
3
2 3
1
K .K
K
149. Two equilibria, AB A B and
2AB B AB are simultaneously maintained in a
solution with equilibrium constants, K1 and K2 respectively.
The ratio of [A+] to [AB2
–] in the solution is
(a) directly proportional to [B–]
(b) inversely proportional to [B–]
(c) directly proportional to the square of [B–]
(d) inversely proportional to the square of [B–]
150. Equilibrium constant (K) for the reaction
Ni(s) + 4CO(g) Ni(CO)4(g) can be written in terms of
(1) Ni(s) + 2CO2 (g) + 2C(s) Ni(CO)4(g);
equilibrium constant = K1.
(2) CO2(g) + C(s) 2CO(g);
equilibrium constant = K2.
What is the relation between K, K2 and K2 ?
(a) K = (K1)/(K2)2 (b) K = (K1 . K2)
(c) K = (K1) (K2)2 (d) K = K1/K2
151. K1, K2 and K3 are the equilibrium constants of the following
reactions (I), (II) and (III) respectively:
(I) N2 + 2O2 2NO2
(II) 2NO2 N2 + 2O2
(III) NO2 2
1 N
2
 + O2
The correct relation from the following is
(a) 1
2 3
1 1K
K K
(b) 1 2
2 3
1 1K
K K
(c) 1 2 3K K K (d) 1 3
2
1K K
K
122 EQUILIBRIUM
152. For the following three reactions a, b and c, equilibrium
constants are given:
(i) 2 2 2 1CO(g) H O(g) CO (g) H (g); K+ +
(ii) 4 2 2 2CH (g) H O(g) CO(g) 3H (g);K+ +
(iii) 4 2 22 3CH (g) 2H O(g) CO (g) 4H (g);K
(a) 1 2 3K K K (b) 2 3 1K K K
(c) K3 = K1 K2 (d) 3 2
3 2 1.K K K
153. The value of equilibrium constant of the reaction
2 2
1 1HI g H (g) I
2 2
 is 8.0
The equilibrium constant of the reaction
2 2H g I (g) 2HI(g) will be:
(a) 1
16
(b) 1
64
(c) 16 (d) 1
8
154. For the reversible reaction,
N2(g) + 3H2(g) 2NH3(g) at 500°C, the value of Kp is
51044.1 when partial pressure is measured in
atmospheres. The corresponding value of KC, with
concentration in mole litre–1, is
(a) 2
5
500082.0
1044.1
(b) 2
5
773314.8
1044.1
(c) 2
5
773082.0
1044.1
(d) 2
5
773082.0
1044.1
155. Two moles of PCl5 were heated in a closed vessel of 2L. At
equilibrium 40% of PCl5 is dissociated into PCl3 and Cl2.
The value of equilibrium constant is
(a) 0.53 (b) 0.267
(c) 2.63 (d) 5.3
156. PCl5 is dissociating 50% at 250°C at a total pressure of
P atm. If equilibrium constant is Kp, then which of the
following relation is numerically correct ?
(a) Kp = 3P (b) P = 3Kp
(c) P = 
2
3
PK
(d) Kp = 
2
3
P
157. For the decomposition of the compound, represented as
2 4 3 2NH COONH ( ) 2NH ( ) CO ( )s g g
the Kp = 2.9 × 10–5 atm3.
If the reaction is started with 1 mol of the compound, the
total pressure at equilibrium would be :
(a) 1.94 × 10–2 atm (b) 5.82 × 10–2 atm
(c) 7.66 × 10–2 atm (d) 38.8 × 10–2 atm
158. The values of Kp1 and Kp2 for the reactions
X Y Z ...(1)
 and A 2B ...(2)
are in the ratio of 9 : 1. If degree of dissociation of X and A
be equal, then total pressure at equilibrium (1) and (2) are in
the ratio :
(a) 3 : 1 (b) 1 : 9
(c) 36 : 1 (d) 1 : 1
159. The dissociation equilibrium of a gas AB2 can be represented
as :
2 22AB (g) 2AB(g) B (g)
The degree of dissociation is ‘x’ and is small compared to 1.
The expression relating the degree of dissociation (x) with
equilibrium constant Kp and total pressure P is :
(a) (2Kp/P) (b) (2Kp/P) 1/3
(c) (2Kp/P)1/2 (d) (Kp/P)
160. On increasing the pressure, the gas phase reaction proceed
forward to re-establish equilibrium, as predicted by applying
the Le Chatelier’s principle. Consider the reaction.
2 2 3N (g) 3H (g) 2NH (g)
Which of the following is correct, if the total pressure at
which the equilibrium is established, is increased without
changing the temperature?
(a) K will remain same
(b) K will decrease
(c) K will increase
(d) K will increase initially and decrease when
pressure is very high
161. The exothermic formation of ClF3 is represented by the
equation :
2 2Cl (g) 3F (g) 32ClF (g) ;
H = – 329 kJ
Which of the following will increase the quantity of ClF3 in
an equilibrium mixture of 2 2 3Cl , F and ClF ?
(a) Adding 2F
(b) Increasing the volume of the container
(c) Removing Cl2
(d) Increasing the temperature
162. When hydrochloric acid is added to cobalt nitrate solution
at room temperature, the following reaction takes place out
the reaction mixture becomes blue. On cooling the mixture it
becomes pink. On the basis of this information mark the
correct answer.
3
2 6
(pink)
CO H O (aq) 4Cl (aq)
2
4 2
(blue)
COCl (aq) 6H O( )l
(a) H > 0 for the reaction
(b) H NH3 > RNH2 > HS–
(b) HS– > RNH2 > NH3 > I–
(c) RNH2 > NH3 > HS– > I–
(d) NH3 > RNH2 > HS– > I–
164. Which equilibrium can be described as an acid-base reaction
using the Lewis acid-base definition but not using the
Bronsted-Lowry definition?
(a) 2NH3 + H2SO4 2NH4
+ + SO4
2–
(b) NH3 + CH3COOH NH4
+ + CH3COO–
(c) H2O + CH3COOH H3O+ + CH3COO–
(d) [Cu(H2O)4]2– + 4 NH3 [Cu(NH3)4]2+ + 4H2O
165. Equal volumes of three acid solutions of pH 3, 4 and 5 are
mixed in a vessel. What will be the H+ ion concentration in
the mixture ?
(a) 1.11 × 10–4 M (b) 3.7 × 10–4 M
(c) 3.7 × 10– 3 M (d) 1.11× 10–3 M
166. The pH of 10–10 M NaOH solution is nearest to:
(a) 6 (b) – 10
(c) 4 (d) 7
167. 100 mL of 0.04 N HCl aqueous solution is mixed with 100 mL
of 0.02 N NaOH solution. The pH of the resulting solution
is:
(a) 1.0 (b) 1.7
(c) 2.0 (d) 2.3
168. Equal volumes of three acid solutions of pH 3, 4 and 5 are
mixed in a vessel. What will be the H+ ion concentration in
the mixture ?
(a) 1.11 × 10–4 M (b) 3.7 × 10–4 M
(c) 3.7 × 10– 3 M (d) 1.11× 10–3 M
169. At 100°C the Kw of water is 55 times its value at 25°C. What
will be the pH of neutral solution? (log 55 = 1.74)
(a) 6.13 (b) 7.00
(c) 7.87 (d) 5.13
170. Ionisation constant of CH3COOH is 1.7 × 10–5 if
concentration of H+ ions is 3.4 × 10–4M, then find out initial
concentration of CH3COOH molecules
(a) 3.4 × 10–4M (b) 3.4 × 10–3M
(c) 6.8 × 10–3M (d) 6.8 × 10–4M
171. Values of dissociation constant, Ka are given as follows :
Acid Ka
HCN 6.2 × 10–10
HF 7.2 × 10–4
HNO2 4.0 × 10–4
Correct order of increasing base strength of the base CN–,
F– and 
_
2NO will be :
(a)
_
2F CN NO (b)
_
2NO CN F
(c)
_
2F NO CN (d)
_
2NO F CN
172. The dissociation constants for acetic acid and HCN at 25°C
are 1.5 × 10–5 and 4.5 × 10–10 respectively. The equilibrium
constant for the equilibrium
CN– + CH3COOH HCN + CH3COO– would be:
(a) 3.0 × 10– 5 (b) 3.0 × 10– 4
(c) 3.0 × 104 (d) 3.0 × 105
173. If degree of dissociation of pure water at 100°C is
1.8 × 10–8, then the dissociation constant of water will be
(density of H2O = 1 gm/cc)
(a) 1 × 10–12 (b) 1 × 10–14
(c) 1.8 × 10–12 (d) 1.8 × 10–14
174. Ionisation of weak acid can be calculated by the formula
(a) 100 aK
c
(b) ( )
100
1 10 apK pH
(c) Both (a) and (b) (d) None of these
175. Equimolar solutions of the following were prepared in water
separately. Which one of the solutions will record the highest
pH ?
(a) SrCl2 (b) BaCl2
(c) MgCl2 (d) CaCl2
176. Solubility product constant (Ksp) of salts of types MX, MX2
and M3X at temperature T are 4.0 × 10–8, 3.2 × 10–14 and
2.7 × 10–15, respectively. Solubilities (mol dm–3) of the salts
at temperature 'T' are in the order –
(a) MX > MX2 > M3X (b) M3X > MX2 > MX
(c) MX2 > M3X > MX (d) MX > M3X > MX2
177. In qualitative analysis, the metals of Group I can be separated
from other ions by precipitating them as chloride salts. A
solution initially contains Ag+ and Pb2+ at a concentration
of 0.10 M. Aqueous HCl is added to this solution until the
Cl– concentration is 0.10 M. What will the concentrations
of Ag+ and Pb2+ be at equilibrium?
(Ksp for AgCl = 1.8 × 10–10, Ksp for PbCl2 = 1.7 × 10–5)
(a) [Ag+] = 1.8 × 10–7 M ; [Pb2+] = 1.7 × 10–6 M
(b) [Ag+] = 1.8 × 10–11 M ; [Pb2+] = 8.5 × 10–5 M
(c) [Ag+] = 1.8 × 10–9 M ; [Pb2+] = 1.7 × 10–3 M
(d) [Ag+] = 1.8 × 10–11 M ; [Pb2+] = 8.5 × 10–4 M
178. The solubility product (Ksp) of the following compounds
are given at 25°C.
Compound Ksp
AgCl 1.1 × 10–10
AgI 1.0 × 10–16
PbCrO4 4.0 × 10–14
Ag2CO3 8.0 × 10–12
The most soluble and least soluble compounds are
respectively.
(a) AgCl and PbCrO4 (b) AgI and Ag2CO3
(c) AgCl and Ag2CO3 (d) Ag2CO3 and AgI
179. What is the molar solubility of Fe(OH)3 if
Ksp = 1.0 ×10–38 ?
(a) 3.16×10–10 (b) 1.386×10–10
(c) 1.45×10–9 (d) 1.12×10–11
124 EQUILIBRIUM
FACT/DEFINITION TYPE QUESTIONS
1. (c) 2. (c) 3. (b)
4. (d) The time taken for complete evaporation depends on
(i) the nature of the liquid, (ii) the amount of the liquid
and (iii) the temperature.
5. (c) When the watch glass is open to the atmosphere, the
rate of evaporation remains constant but the molecules
are dispersed into large volume of the room. As a
consequence the rate of condensation from vapour to
liquid state is much less than the rate of evaporation.
6. (c) Ice melts with a reduction in volume. So Increase in
pressure shifts equilibrium to water side, result in
melting of ice according to Lechatelier's principle.
7. (a) A reaction is said to be in equilibrium when rate of
forward reaction is equal to the rate of backward
reaction.
8. (c)
9. (b) The reaction mixtures starting either with H2 or D2
reach equilibrium with the same composition,except
that D2 and ND3 are present instead of H2 and NH3.
10. (a) Equilibrium can be attained by either side of the
reactions of equilibrium.
11. (d) According to the idea of dynamic equilibrium there is
possibility of formation of all product.
12. (b) At equilibrium, the rate of forward and backward
reactions is equal.
13. (a) For reation (1)
2
1
2 2
[NO]K
[N ][O ]
=
and for reaction (2)
½ ½
2 2
2
[N ] [O ]
K
[NO]
= therefore 1 2
2
1K
K
=
14. (c) N2 + 3H2 2NH3
K = [NH3]2 / [N2] [H2]3 .... (i)
2 2 3
1 3N H NH
2 2
1/ 2 3/ 2
3 2 2' [NH ]/[N ] [H ]K .... (ii)
Dividing equation (i) by equation (ii), we get K' =
K
15. (b) Given reaction, 2A B C
c 2
[B][C]K
[A]
3 3
c 3 2
2 10 3 10K
(10 )
= 6
16. (c) A2 + B2 2AB 
2
c
2 2
[AB]K
[A ][B ]
3 2 2
c 3 3
(2.8 10 ) (2.8)K 0.62
3 4.23 10 4.2 10
17. (c) A + B C + D
At eqb. x x 2x 2x
Kc = 4
x.x
x2.x2
18. (a) For A B C, n 1 2 1
Unit of 
n 1
c
mol molK
litre litre
 = Litre mole–1
19. (c) Kp = 
2
p
2
P CO 4 4;K 8; C(s) 1;
PCO 2
The concentration of solids and liquids are taken as
unity.
20. (d) 22C(s) +O ( )g 2 2CO ( )g
n = 2 – 1 = + 1
Kc and Kp are not equal.
21. (b) For a gaseous phase reaction Kp and Kc are related as
( ) gn
p cK K RT
For the given reaction,
CO(g) + 2
1 O ( )
2
g CO2(g)
ng = 1– (1 + 0.5) = – 0.5 or 
1
2
 Kp = Kc
1
2( )RT
or p
c
K
K
 = 
1
2( )RT
22. (c) Using the relation KP = KC. (RT) n, we get
( ) nP
C
K
RT
K
Thus 
P
C
K
K will be highest for the reaction having
highest value of n.
EQUILIBRIUM 125
The n values for various reactions are
(a) n 1 11– 1 –
2 2
(b) n = 2 – (1 + 1) = 0
(c) n = (1 +1) – 1= 1
(d) n = (2 + 4) – (7 + 2) = – 3
Thus maximum value of n = 1
23. (c) As Kp = Kc 
gnRT
Here ng = 1
So, Kp = Kc when RT = 1
Thus T = 12.5 K
24. (b) 3Fe(s) + 4H2O (steam) Fe3O4 (s) + 4 H2 (g)
Kp = 2
2
4
H
4
H O
(p )
(p )
 only gaseous products and reactants.
25. (b) C(s) + CO2(g) 2CO(g)
Apply law of mass action,
2
2 2
22
COCO
P
CO CO
(10P )(P )
K or 63
P P
(Given KP = 65) and PCO = 
2CO10P
or 2
2
2
2
CO
CO
CO
100(P )
63 or 63 100 P
P
2CO
63P 0.63 atm
100
2CO COP 10P = 10 × 0.63 = 6.3 atm
Ptotal = 2CO COP P = 0.63 + 6.3 = 6.93 atm.
26. (d) Rate constant of forward reaction (Kf) = 1.1 × 10–2 and
rate constant of backward reaction (Kb) = 1.5 × 10–3
per minute.
Equilibrium constant (Kc) 33.7
105.1
101.1
K
K
3
2
b
f
27. (a) )g(CO)s(MgO)s(MgCO 23
MgO & MgCO3 are solid and they donot exert any
pressure and hence only pressure exerted is by CO2.
Therefore 2COP PK
28. (a) All the reactants and products are in same physical
state.
29. (a)
1
1 34
4 1 4
[Ni(CO) ] mol lK (mol l )
[CO] (mol l )
30. (b) For the reaction
CaCO3 (s) CaO (s) + CO2 (g)
On the basis of the stoichiometric equation, we can
write,
Kc =[CaO(s)] [CO2(g)/[CaCO3(s)]
Since [CaCO3(s)] and [CaO(s)] are both constant,
therefore modified equilibrium constant for the thermal
decomposition of calcium carbonate will be
Kć = [CO2(g)]
K p = [p CO2(g)]
31. (d) Equilibrium constant (K) is independent of
concentrations of reactions and products.
32. (a) Equilibrium constant is not effected by change in
conditions like P and V. These changes can change
only the time required to attain equilibrium.
33. (b) Reaction proceed forward according to Le-chatelier’s
principle.
34. (b)
35. (d) For reaction to proceed from right to left
cQ K i.e the reaction will be fast in backward
direction i.e rb > rf.
36. (b) The equilibrium constant helps in predicting the
direction in which a given reaction will proceed at any
stage. For this purpose, we calculate the reaction
quotient Q. The reaction quotient Q (Qc with molar
concentration and Qp with partial pressures) is defined
in the same way as the equilibrium constant Kc except
that the concentrations in Qc are not necessary
equilibrium values.
37. (d)
38. (c) Both (a) and (b) are correct for the equation,
K = G /RTe
39. (c) G = –2.303 RT log K
–nFE° = –2.303 RT log K
nFE (I)log K
2.303 RT
 
nFE0.4342
RT
........ (i)
nFEln K
RT
nFE
RTK e ....... (ii)
40. (d) Solid Liquid
It is an endothermic process. So when temperature is
raised, more liquid is formed. Hence adding heat will
shift the equilbrium in the forward direction.
41. (d) According to Le-chatelier's principle" whenever a
constraint is applied to a system in equilibrium, the
system tends to readjust so as to nullify the effect of
the constraint.
42. (b) The most favourable conditions are :
(i) High pressure ( na
base.
67. (c)
68 (a) (i) 
2 11 2
3 4 2 3 2 4
base baseacid acid
H PO H O H O H PO
(ii) 
1 2 1 2
2 4 2 4 3
acid base base acid
H PO H O HPO H O
(iii) 
2 21 1
2 4 3 4
acid basebase acid
H PO OH H PO O
Hence only in (ii) reaction H2PO4
– is acting as an acid.
69. (b) The value of ionic product of water changes with the
temperature.
70. (a) Given : Hydroxyl ion concentration
[OH–] = 0.05 mol L–1. We know that
14101]OH][H[
or 13
14
102
05.0
101]H[ mol L–1
 We also know that
]102[log]Hlog[pH 13
= 10log)13(2log10log2log 13
.6990.120000.133010.0
Since the value of pH > 7, therefore the solution is
basic.
71. (b)
72. (b) pH = – log [H+] = 
1log
H
73. (c) On dilution [H+] = 10–6 M = 10–6 mol
Now dissociation of water cannot be neglected,
Total [H+] = 10–6 + 10–7 = 11 × 10–7
pH = –log [H+]
 = –log (11× 10–7) = 5.98
74. (d) pH = 1 ; H+ = 10–1 = 0.1 M
pH = 2 ; H+ = 10–2 = 0.01 M
M1 = 0.1 V1 = 1
 M2 = 0.01 V2 = ?