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CBSE Questions for Class 11 Medical Chemistry Equilibrium Quiz 10 - MCQExams.com

Calculate ionisation constant for pyridinium chloride,
Given that H+ ion concent ration is 3.6×104M and its concentration is 0.02M.
  • 6.4×102
  • 6.4×106
  • 6.4×108
  • 12×108
pH of water is 7.0 at 25C. If water is heated to 70C, the
  • pH will decrease and the sample becomes acidic.
  • pH will increase but the sample will remain neutral.
  • pH will remain constant as 7.
  • pH will decrease but the sample will remain neutral.
In comparison of ferrous salts, ferric salts are:
  • more stable
  • less stable
  • equal stable
  • none of these
Which of the following statements is not true for Mohr's salt?
  • It decolourises KMnO4 solution
  • It is a double salt
  • Oxidation state of iron is +3
  • It is a primary standard
pH of 0.01M(NH4)2SO4) and 0.02MNH4OH buffer (pKa of NH+4=9.26) is
  • 9.26+log2
  • 9.26log2
  • 4.74+log2
  • 9.26
The conjugate base of sulphuric acid is _________
  • Sodium hydroxide
  • Hydrochloric acid
  • Bisulphate ion
  • Barium hydroxide
In which of the following solutions, ions are present
  • Sucrose in water
  • Sulphur in CS2
  • Caesium nitrate in water
  • Ethanol in water
Pure NaCl is prepared by saturating a cold saturated solution of common salt in water with HCl gas. The principle used is
  • Le Chatelier principle
  • Displacement law
  • Common ion effect
  • Fractional distillation
Sodium chloride is purified by passing hydrogen chloride gas in an impure solution of sodium chloride. It is base on
  • Buffer action
  • Common ion effect
  • Association of salt
  • Hydrolysis of salt
The degree of dissociation in a weak electrolyte increases________
  • on increasing dilution
  • on increasing pressure
  • on decreasing dilution
  • none of these
To obtain a buffer which be suitable for maintaining a pH of about 45, we need to have in solution a mixture of
  • A strong base + its salt with a weak acid
  • A weak base + its with a strong acid
  • A strong acid+ its salt with a weak base
  • A weak acid+its salt with a strong base
Which of the following is a buffer?
  • NaOH+CH3COONa
  • NaOH+Na2SO4
  • K2SO4+H2SO4
  • NH4OH+NH4Cl
Amongst the following the buffer solution is______
  • NH4Cl+NH4OH solution
  • NH4Cl+NaOH solution
  • NH4OH+HCl solution
  • NaOH+HCl solution
At 25oC the pH value of a solution is 6. The solution is
  • Basic
  • Acidic
  • Neutral
  • Both (b) and (c)
A buffer solution is a mixture of 
  • Strong acid and strong base
  • Weak acid and weak base
  • Weak acid and conjugate acid
  • Weak acid and conjugate base
Le-chatelier principle is applicable 
  • Both for physical and chemical equilibrium
  • Only for chemical equilibrium
  • Only for physical equilibrium
  • Neither for (b) nor for (c)
The ionisation constant of phenol is higher than that of ethanol because___________
  • Phenoxide ion is bulkier than ethanoxide
  • Phenoxide ion is stronger base than ethanoxide
  • Phenoxide ion is stabilised through delocalisation
  • Phenoxide ion is less stable than ethoxide
A solution that resists changes in pH upon the addition of a small amount of strong acid or strong base known as_____
  • A colloid
  • A crystalloid
  • A buffer
  • A indicator
Which one is buffer solution
  • [PO4][HPO4]
  • [PO33][H2PO4]
  • [HPO4][H2PO4]
  • All of these
Which one of the following is not a buffer solution?
  • 0.8 M H2S+0.8 M KHS
  • 2 M C6H5NH2+2M C6H5 NH+3Br
  • 3 M H2CO3+3 M KHCO3
  • 0.05 M KClO4+0.05 M HClO4
Which of the following will produce a buffer solution when mixed in equal volumes?
  • 0.1mol dm3 NH4OH and 0.1mol dm3 HCl.
  • 0.05mol dm3 NH4OH and 0.1mol dm3 HCl.
  • 0.1mol dm3 NH4OH and 0.05mol dm3 HCl.
  • 0.1mol dm3 CH4COONa and 0.1mol dm3 NaOH.
The main salt soluble in sea water is 
  • MgCl2
  • NaCl
  • MgSO4
  • CaSO4
State true or false 
Salts are neutral.
  • True
  • False
Why curd and other sour substances should not be stored in brass and copper vessels?
  • Curd and sour substances contain bases
  • Curd and sour substances contain acids
  • Both A and B
  • None of A or B
If first dissociation of X(OH)3 is 100% whereas second dissociation is 50% and third dissociation is negligible then the pH of 4×103 M X(OH)3 is :
  • 11.78
  • 10.78
  • 2.5
  • 2.22
Solubility product of Al(OH)3 and Zn(OH)2 are 8.5×1023 and 1.8×1014 respectively. If both Al3+ and Zn2+ ions are present in a solution, which one will precipitate first on addition of NH4OH?
  • Al(OH)3
  • Zn(OH)2
  • Mg(OH)2
  • Ca(OH)2
The dissociation of water at 25C is 1.9×107% and the density of water is 1.0 g/cc. The ionisation constant of water is :
  • 3.42×106
  • 3.42×108
  • 1.00×1014
  • 2.00×1016
Which of the following statements is correct?
  • The pH of 1.0×108M solution of HCl is 8
  • The conjugate base of H2PO24 is HPO24
  • Autoprotolysis constant of water increases with temperature
  • When a solution of weak monoprotic acid is titrated against a strong base, at half neutralization point pH=12pKa
Total number of moles for the reaction  2HI H2+I2, if α  is degree of dissociation is :
  • 2
  • 2α
  • 1
  • 1α
If the dissociation constant of a weak acid is 1.0×105, then the equilibrium constant for the reaction of the acid with a strong base is:
  • 1.0×105
  • 1.0×109
  • 1.0×109
  • 1.0×1014
The solubility product of BaSO4 is 1.5×109. The precipitation in a 0.01M Ba2+ solution will start on adding H2SO4 of concentration:
  • 1×109M
  • 1.5×107M
  • 2×107M
  • 1×106M
A precipitate of calcium oxalate will not dissolve in:
  • HCl
  • HNO3
  • aquaregia
  • CH3COOH
Blood pH is controlled by the concentrations of H2CO3 and HCO3. In the presence of NaHCO3, pH of blood: 
  • increases
  • decreases
  • does not change
  • first decreases and then increases
pH of 0.01M(NH4)2SO4 and 0.02M NH4OH buffer (pKa (NH+4)=9.26) is
  • 9.26+log1
  • 9.26+log2
  • 4.74
  • 4.74+log2
If pKb For CN at 25oC  is 4.The pH of 0.5M aqueous NaCN solution is:-
  • 12
  • 10
  • 11.5
  • 11
Which of the following mixture is not a buffer solution?
  • 100 ml of 0.5 NH4Cl and 100 ml of 0.6 N NH4OH
  • 100 ml of 0.6 N  HCN and 100 ml of 0.4 N NaOH
  • 100 ml of 0.2 N NH4OH and 100 ml of 0.2 N CH3COOH
  • 100 ml of 0.4 N HCl and 100 ml of 0.4 N NaOH
A solution contains 0.09 M HCl, 0.09 M CHCl2COOH, and 0.1 M CH3COOH. If total [H+]=0.1 and Ka for CH3COOH=105, Ka for CCl2HCOOH is:
  • 1.35×104
  • 0.18×102
  • 0.18×105
  • 1.25×102
The degree of dissociation of 0.1 M weak acid HA is 0.5%. If 2 ml of 1.0 M HA solution is diluted to 32 ml, the degree of dissociation of acid and H3O+ ion concentration in the resulting solution will be respectively:
  • 0.02 and 3.125×104
  • 1.25×103 and 0.02
  • 0.632 and 3.95×104
  • 0.02 and 8.0×1012
The first and second dissociation constants of an acid H2A are 1.0×105 and 5.0×1010 respectively. The overall dissociation constant of the acid will be:
  • 5.0×105
  • 5.0×1015
  • 5.0×1015
  • 2.0×105
The degree of dissociation of an electrolyte is :
  • directly proportional to its concentration
  • directly proportional to the square of its concentration
  • inversely proportional to its concentration
  • inversely proportional to the square root of its concentration
What is the Kb of a weak base that produces an OH per molecule if a 0.05 M solution is 2.5% ionized?
  • 7.8×108
  • 1.6×106
  • 3.125×105
  • 1.2×103
If the degree of dissociation of water at 90C is 1.28×108, then the ionization constant of water at 90C is:
  • 1.28×1014
  • 12.81×1015
  • 9.07×1015
  • 7.52×1012
The dissociation constants of a weak acid HA and weak base BOH are 2×105 and 5×106 respectively. The equilibrium constant for the neutralisation reaction of the two is :
  • 1.0×104
  • 1.0×104
  • 1.0×1010
  • 2.5×101
Aqueous solutions of HNO3,KOH,CH3COOH and CH3COONa of identical concentrations are provided. The pair(s) of solutions which form a buffer upon mixing are:
  • HNO3 and CH3COOH
  • KOH and CH3COONa
  • HNO3 and CH3COONa
  • CH3COOH and CH3COONa
Silver ions are added to the solution with
[Br]=[Cl]=[CO23]=[AsO34]=0.1M
Which compound will precipitate at the lowest [Ag+] ?
  • AgBr(Ksp=5×1013)
  • AgCl(Ksp=1.8×1010)
  • Ag2CO3(Ksp=8.1×1012)
  • Ag3AsO4(Ksp=1022)
The initial rate of hydrolysis methyl acetate (1 M) by a weak acid (HA, 1M) is 1/100th of that of a strong acid (HX, 1M), at 25oC. The Kaof HA is:
  • 1 x 104
  • 1 x 105
  • 1 x 106
  • 1 x 103
From application of thermodynamics on chemical reaction,
we get ΔG=ΔG0+RT ln Q
Also ΔG=ΔHTΔS.
If ΔG=0, reaction is at equilibrium.
If ΔG>0 reaction is non-spontaneous under given condition. IfΔG<0, reaction is spontaneous under given condition.
Consider the reaction given below.
A(s)2B(g)         ΔH0=160 KJ/mol.
ΔS0=400 J/mol-K  at 400 K
Which of the following is correct at 400 K?
  • On adding more A(s), more B(g) is produced, when A(s) and B(g) were in equilibrium
  • The equilibrium constant at 400 K can't be found
  • The reaction is at equilibrium at 400 K and standard condition
  • The ΔG of the reaction is greater than zero, at 400 K and standard condition
Find the concentration of H+ ions in an aqueous solution, which is saturated with H2S (0.1M) as well as H2CO3 (0.2M). 
[Use data: K1=107,K2=1014 for H2S,K1=4×107,K2=4×1011 for H2CO3]
  • 3×104M
  • 3.83×104M
  • 2.83×104M
  • None of these
White salt is readily soluble in water and gives a colourless solution with pH of about 9. The salt would be:
  • NH_4NO_3
  • CH_3COONa
  • CH_3COONH_4
  • CaCO_3
Concentration of H^+ ions in 0.1 M H_2CO_3 is (K_{1}=4\times10^{-7},K_{2}=4\times10^{-11}):



  • 2\times10^{-4}M
  • 4\times10^{-9}M
  • 2\times10^{-3}M
  • None of these
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