ALLEN CHEMISTRY ALLEN Study Package For – JEE (Advanced) JEE-Chemistry EXERCISE-01 CHECK YOUR GRASP SELECT THE COR
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ALLEN
CHEMISTRY ALLEN Study Package For – JEE (Advanced)
JEE-Chemistry EXERCISE-01
CHECK YOUR GRASP
SELECT THE CORRECT ALTERNATIVE (ONLY ONE CORRECT ANSWER) 1. Which of the following expressions is/are not true ? (A) [H +] = [OH – ] =
K w for a neutral solution at all temperatures.
(B) [H +] >
K w & [OH –]
S 2 > S 3 > S 4
(B) S 1 > S 2 = S 3 > S 4
(C) S 1 > S 3 > S 2 > S 4
(D) S 4 > S 2 > S 3 > S 1
The solubility product Mg(OH) 2 in water at 25 °C is 8.9 × 10 –13 (mole dm –3 ) 3 while that of Al(OH) 3 is 5 × 10 –33 (mol dm –3 ) 4 . If S 1 and S 2 are the solubilities of Mg(OH) 2 and Al(OH) 3 in water in mol dm –3 at 25 °C, what is the order of magnitude of the ratio, S 1/S 2 ? (A) 10 5
50.
(C) 6 × 10 –4 M
(A) 1.3 × 10 2 , 1.7 × 10 –5 M
(A) 3.4 × 10 –12 M 47.
(B) 1.2 × 10 10 M
At 25 °C, the solubility product values of AgCl and AgCNS are 1.7 × 10 –10 and 1.0 × 10 –12 respectively. When water is saturated with both solids, calculate the ratio [Cl –]/[CNS –] and also [Ag +] in the solution.
(A) 108 x 2 45.
2
The solubility product of BaCrO4 is 2.4 × 10 M . The maximum concentration of Ba(NO3)2 possible without precipitation in a 6 × 10 –4 M K 2CrO 4 solution is-
(A) 4.80 × 10 –8 43.
(D) (ii) < (iii) < (iv) < (i) –10
(A) 4 × 10 –7 M 41.
(iv) pure water
(B) (iii) < (ii) < (i) < (iv)
(C) (iii) < (ii) = (i) < (iv) 40.
(D) 0.1 M H 2SO 4
(B) 10 4
(C) 10 6
(D) 10 3
When HCl gas is passed through a saturated solution of common salt, pure NaCl is precipitated because(A) HCl is highly ionised in solution (B) HCl is highly soluble in water (C) the solubility product of NaCl is lowered by HCl (D) the ionic product of [Na +] [Cl –] exceeds the solubility product of NaCl
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JEE-Chemistry 51.
A certain indicator (an organic dye) has pKa = 5. For which of the following titrations may it be suitable. (A) acetic acid against NaOH (B) aniline hydrochloride against NaOH (C) sodium carbonate against HCl (D) barium hydroxide against oxalic acid
52.
The pH indicators are(A) salts of strong acids & strong bases (B) salts of weak acids & weak bases (C) either weak acids or weak bases (D) either strong acids or strong bases
54.
What fraction of an indicator Hln is in the basic form at a pH of 6 if pK a of the indicator is 5 ? 1 1 10 1 (A) (B) (C) (D) 2 11 11 10 An acid-base indicator which is a weak acid has a pKa value = 5.5. At what concentration ratio of sodium acetate to acetic acid would the indicator show a colour half-way between those of its acid and conjugate base forms ? pK a of acetic acid = 4.75 (A) 4.93 : 1
(B) 6.3 : 1
ANSWER
C HE C K Y OU R G R ASP Que.
1
2
(C) 5.62 : 1
3
4
5
6
7
8
(D) 2.37 : 1
KEY 9
E XE R CISE - 1 10
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JEE-Chemistry EXERCISE–02
BRAIN TEASERS
SELECT THE CORRECT ALTERNATIVES (ONE OR MORE THEN ONE CORRECT ANSWERS) 1.
The conjugate acid of NH 2– is(A) NH 3
2.
(II) OH–
(iii) H2PO 4–
(IV) HCO3–
(A) I, III, IV
(B) I and III
(C) III and IV
(D) All
pH of an aqueous solution of NaCl at 85 °C should be(B) > 7
10 mL of (A) 1
6.
(B) 3
(C) 4
(B) 3.52 × 10 –3
(C) 6.75 × 10 –4
(B) [H + ] =
–2
(D) [H + ] = 3[PO 43– ]
NODE6\E:\Data\2014\Kota\JEE-Advanced\SMP\Che\UNIT-07\IONIC EQUILIBRIUM & ACID BASE\Eng\Exercise.p65
(B) 50 %
(C) 25 %
(D) none of these
What is the percentage hydrolysis of NaCN in N/80 solution when the dissociation constant for HCN is 1.3 × 10 –9 and K w = 1.0 × 10 –14 (A) 2.48
(B) 5.26
(C) 8.2
(D) 9.6 + 4
pH of 0.01 M (NH 4 ) 2SO 4 and 0.02 M NH 4 OH buffer solution (pK a of NH = 9.26) is(A) 9.26
11.
K 1 [H 3 PO 4 ]
The degree of hydrolysis of a salt of weak acid and weak base in it's 0.1 M solution is found to be 50%. If the molarity of the solution is 0.2 M, the percentage hydrolysis of the salt should be(A) 100 %
10.
(D) 5.38 × 10 –2
If K 1 & K 2 be first and second ionisation constant of H 3PO 4 and K 1 >> K 2 which is incorrect-
(C) K 2 = [HPO 4 ]
9.
(D) 1
If pKb for fluoride ion at 25 °C is 10.83, the ionization constant of hydrofluoric acid in water at this temperature is-
(A) [H + ] = [H 2 PO 4– ]
8.
(D) 0
M M H 2SO 4 is mixed with 40 mL of H 2SO 4 . The pH of the resulting solution is200 200 (B) 2 (C) 2.3 (D) none of these
(A) 1.74 × 10 –5 7.
(C) < 7
1 CC of 0.1 N HCl is added to 99 CC solution of NaCl. The pH of the resulting solution will be(A) 7
5.
(D) N 2 H 4
(I) HPO3
(A) 7 4.
(C) NH 4
Out of the following, amphiprotic species are 2–
3.
+
(B) NH 2 OH
(B) 4.74
(C) 4.74 + log 2
(D) none
The range of most suitable indicator which should be used for titration of X –Na + (0.1 M, 10 mL) with 0.1 M HCl should be (Given : k b(X ) = 10 –6 ) (A) 2 – 3
12.
(B) 3 – 5
(C) 6 – 8
(D) 8-10
When NO 2 is bubbled into water, If dispropor tionates completely into HNO 2 and HNO 3 . 2NO 2 + H 2 O() HNO 2 (aq.) + HNO 3 (aq.) The concentration of NO 2– in a solution prepared by dissolving 0.05 mole of NO 2 gas in 1 litre H 2O is {K a(HNO 2) = 5 × 10 –4 }
13.
(A) ~ 5 × 10 –4
(B) ~ 4.8 × 10 –5
(C) ~ 4.8 × 10 –3
(D) ~ 2.55 × 10 –2
If K sp for HgSO 4 is 6.4 × 10 –5, then solubility of this substance in mole per m 3 is(A) 8 × 10 –3
14.
(B) 6.4 × 10 –5
(C) 8 × 10 –6
(D) none of these
Which of the following is most soluble in water ? (A) MnS(K sp = 8 × 10 –37 )
(B) ZnS(K sp = 7 × 10 –16 )
(C) Bi 2 S 3 (K sp = 1 × 10 –72 )
(D) Ag 3 (PO 4 ) (K sp = 1.8 × 10 –8 )
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JEE-Chemistry 15.
How many moles NH3 must be added to 2.0 litre of 0.80 M AgNO3 in order to reduce the Ag+ concentration + to 5 × 10 –8 M. K f of [Ag(NH 3 ) 2 ] = 10 8 (A) 0.4
16.
(B) 2
(C) 3.52
(D) 4
The solubility product of BaF 2 has the value, 1.7 × 10 –4 . If V 1 mL of BaCl 2 Solution (10 –1 M) and V2 mL of NaF solution (10–2 M) are mixed, what is the ratio V1 : V2 so that a precipitate may be obtained ? (A) 1 : 1 (B) 2 : 1 (C) 1 : 2 (D) precipitate cannot obtained for any possible ratio
18.
At 18 °C, the solubility of CdS in water is 6.33 × 10 –15 M. What is the concentration of Cd + ion in a solution of pH = 1 saturated with H 2S gas, in which concentration of H 2S = 0.1 M ? The product of the first and second ionization constants of H 2S is 1.1 × 10 –22 at this temperature. (A) 6.343 × 10 –8 M
(B) 4. 368 × 10 –8 M
(C) 4.368 × 10 –9 M
(D) 3.643 × 10 –8 M
100 mL of 0.02 M benzoic acid (pKa = 4.2) is titrated using 0.02 M NaOH. pH after 50 mL and 100 mL of NaOH have been added are(A) 3.50,7
19.
(B) 4.2, 7
(B) 0.7
(B) 3.7
(D) 13.7
(C) 4.7
(D) 5.7
A well is dug in a bed of rock containing fluorspar (CaF 2). If the well contains 20000 L of water, what is the amount of F – in it ? K sp = 4 × 10 –11 (A) 4.3 mol
22.
(C) 5.3
10.2 g of acetic anhydride was added to 989.8 g of water to make a solution with a density of 1g/mL. If the k a of acetic acid is 2 × 10 –5 , the pH of the solution would be [C = 12, H = 1, O = 16] (A) 2.7
21.
(D) 4.2, 8.25
What is the pH of solution made by adding 3.9 g NaNH 2 into water to make a 500 mL solution K b (NH 3 ) = 2 × 10 –5 [Na = 23, N = 14, H = 1] (A) 13.3
20.
(C) 4.2, 8.1
(B) 6.8 mol
(C) 8.6 mol
If HA + NaOH NaA + H 2 O
H = – 12 kcal
and HB + NaOH NaB + H 2 O
H = –11 kcal
(D) 13.6 mol
then equimolar solution of which acid has higher pH -
23.
(A) HA
(B) HB
(C) both have same pH
(D) information insufficient
Aniline behaves as a weak base. When 0.1 M, 50 mL solution of aniline was mixed with 0.1 M, 25 mL solution of HCl the pH of resulting solution was 8. Then the pH of 0.01 M solution of aniliniumchloride will be (K w = 10 –14 ) (A) 6
24.
(B) 6.5
(B) 150 mL
(C) 100 mL
(D) 50 mL
What is the difference in pH for 1/3 and 2/3 stages of neutralisation of 0.1 M CH 3COOH with 0.1 M NaOH. (A) – 2 log 3
26.
(D) 5.5
pH of a mixture of 1 M benzoic acid (pK a = 4.20) and 1M C 6 H 5 COONa is 4.5, what is the volume of benzoic acid required to prepare a 300 mL buffer [log 2 = 0.3] ? (A) 200 mL
25.
(C) 5
(B) 2 log (1/4)
(C) 2 log (2/3)
(D) – 2 log 2
–5
An acid HA (k a = 10 ) reacts with NaOH at 298 K. What would be the value of the rate constant of the reverse reaction at the same temperature if the rate constant of the forward reaction is 10 –11 mol –1 L sec –1 ? (A) 10 –9
(B) 10 9
(C) 10 –5
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(D) 10 –20
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JEE-Chemistry 27.
28.
The pH of 1.0 M NaHSO4 solution will be (given that K1 and K2 for H2SO4 equal to and 10–2 respectively)(A) nearly 1.0
(B) between 2 and 3
(C) between 1.2 and 1.8
(D) between 3 and 4
0.1 millimole of CdSO4 are present in 10 mL acid solution of 0.08 N HCl. Now H2S is passed to precipitate all the Cd 2+ ions. The pH of the solution after filtering off precipitate, boiling off H 2S and making the solution 100 mL by adding H 2O is(A) 2
29.
30.
(B) 4
(D) 8
Zn salt is mixed with (NH 4 ) 2 S of molarity 0.021 M. The amount of Zn 12 mL of this solution would be (Given : K SP ZnS = 4.51 × 10 –24 ) (A) 1.677 × 10 –22 g
(B) 1.767 × 10 –22 g
(C) 2.01 × 10 –23 g
(D) none of these
2+
remains unprecipitated in
+
The self ionisation constant for pure formic acid, K = [HCOOH 2 ] [HCOO – ] has been estimated as 10–6 at room temperature. The density of formic acid is 1.22 g/cm3. The percentage of formic acid molecules in pure formic acid that are concer ted to formate ion would be(A) 0.002 %
NODE6\E:\Data\2014\Kota\JEE-Advanced\SMP\Che\UNIT-07\IONIC EQUILIBRIUM & ACID BASE\Eng\Exercise.p65
(C) 6
(B) 0.004 %
(C) 0.006 %
ANSWER
B RAIN T EASER S
(D) 0.008 %
KEY
E XE R CISE - 2
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JEE-Chemistry
EXERCISE–03
MISCELLANEOUS TYPE QUESTIONS
TRUE / FALSE
2.
When a solution of a weak monoprotic acid is titrated against a strong base, at half-neutralization point, 1 pH = pK a 2 A solution of sodium acetate and ammonium acetate can act as a buffer.
3.
If the solubility of the salt Li 3Na 3 (AlF 6) 2 is x, then its solubility product would be 2916 x 8 .
4.
A buffer has maximum buffer capacity when the ratio of salt to acid is 10.
5.
In the presence of a common ion (incapable of froming complex ion), the solubility of salt decreases.
6.
The ionic product of water changes if a few drops of acid or base are added to it.
7.
When equilibrium is attained, the concentration of each of the reactants & products become equal.
8.
The reaction, HCN + OH – CN – + H 2O is displaced to the right indicating that the acid strength of HCN is greater than water & the base strength of CN – is greater than that of OH – .
9.
The hydroxyl ion is hydrated to give several ionic species like H 2O 2 , H 3O 3 and H 4 O 4 .
10.
Ostwald's dilution formula is applicable to weak as well as strong electrolytes.
11.
CO 2 is a Lewis base
12.
Solution whether neutral, acidic or basic contain both H + & OH – ions.
13.
The ionic product of a saturated solution is equal to solubility product constant of its solute.
14.
A Lewis base is a substance which can donate a pair of electrons ?
15.
If ionic product is less than k sp, no precipitation will occur.
16.
A buffer has definite pH value which changes on keeping it or on diluting it.
17.
A salt of strong acid with a strong base does not undergo hydrolysis
18.
HCl does not act as an acid in benzene
19.
Water acts as a base when ammonia is dissolved in it.
20.
In the reaction, SnCl 4 + 2Cl – [SnCl 6] 2– , SnCl 4 is a Lewis acid.
21.
The strength of an oxy acid increases with increase in the EN value of central atom.
22.
In aqueous solution the hydronium ion is further hydrated to give species like H 5O 2 , H 7 O 3 and H 9O 4
–2
–3
–4
+
+
+
FILL IN THE BLANKS 1. 2. 3. 4. 5.
6.
In a mixture of weak acid and its salt, the ratio of concentration of salt to acid is increased ten fold. The pH of the solution would ....... by ....... unit. The solubility of CH 3COOAg in water considering hydrolysis of CH 3COO– ions would be ....... than that ignoring the hydrolysis. From an equimolar solution of Cl – and Br – ions, the addition of Ag + will selectively precipitates ....... (K sp of AgCl & AgBr are 1 × 10 –10 & 1 × 10 –13 respectively). The solubility of AgCl in NH3 is ...... than the solubility in pure water because of complex ion, [Ag(NH3)2]+ formation. The hydrolytic constant K h for the hydrolytic equilibrium – H 2 PO 4 + H 2 O H 3 PO 4 + OH – is 1.4 × 10 –12 – The value of ionization constant for the H 3PO 4 + H 2O H 2PO 4 + H 3 O + is ...................... . Given the equilibrium constants Cl – + HgCl +
HgCl 2
HgCl 2 + Cl –
HgCl 3
–
K 1 = 3 × 10 6
;
; K 2 = 8.9
The equilibrium constants for the dispropotionation equilibrium. 2HgCl 2
–
HgCl + + HgCl 3
is -
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JEE-Chemistry 7.
If the salts M 2X, QY 2 and PZ 3 have same solubilities (