Solubility of MX2-type eletrolytes is 0.5 × 10–4 mole/lit, then find out Ksp of electrolytes 
Given s = 0.5 × 10–4 moles/lit
Which has the highest value of pH? 
Na2CO3 is a salt of weak acid H2CO3 and strong base NaOH, therefore, its aqueous solution will be basic hence has pH more than 7.
Solution of 0.1 N NH4OH and 0.1 N NH4Cl has pH 9.25. Then find out pKb of NH4OH 
but pOH+ pH = 14 or pOH = 14 – pH
14 – 9.25 – 0 = pKb pKb = 4.75
The reaction quotient (Q) for the reaction
is given by
The reaction will proceed from right to left if 
where Kc is the equilibrium constant
For reaction to proceed from right to left
i.e the reaction will be fast in backward direction i.e rb > rf.
Which one of the following orders of acid strength is correct? 
The higher is the tendency to donate proton, stronger is the acid. Thus the correct order is R – COOH > HOH > R – OH > CH ≡ CH depending upon the rate of donation of proton.
Which one of the following compounds is not a protonic acid? 
B(OH)3 does not provide H+ ions in water instead it accepts OH– ion and hence it is Lewis acid
The solubility product of AgI at 25ºC is 1.0 × 10–16 mol2 L–2. The solubiliy of AgI in 10–4 N solution of KI at 25ºC is approximately(in mol L–1) 
Ksp for AgI = 1 × 10–16 In solution of KI, I– would be due to the both AgI and KI, 10–4 solution KI would provide = 10–4 I–
AgI would provide, say = x I– (x is solubility of AgI)
as x is very small ∴ x2 can be ignored
∴ 10–4 x = 10–16
The solubility product of a sparingly soluble salt AX2 is 3.2 x 10-11 . Its solubility ( in moles/litre) is
The rapid change of pH near the stoichiometric point of an acid-base titration is the basis of indicator detection. pH of the solution is related to ratio of the concentrations of the conjugate acid (HIn) and base (In–) forms of the indicator by the expression 
For an acid-base indicator
Taking negative on both sides
or we can write
H2S gas when passed through a solution of cations containing HCl precipitates the cations of second group of qualitative analysis but not those belonging to the fourth group. It is be cau se 
IVth group needs higher S2– i on concentration. In presence of HCl, the dissociation of H2S decreases hence produces less amount of sulphide ions due to common ion effect, thus HCl decreases the solubility of H2S which is sufficient to precipitate IInd group radicals.
What is the correct relation ship between the pHs of isomolar solutions of sodium oxide (pH1), sodium sulphide (pH2), sodium selenide (pH3) and sodium telluride (pH4)? [2 00 5]
The solution formed from isomolar solutions of sodium oxide, sodium sulphide, sodium selenide H2O, H2S, H2Se & H2Te respectively.
As the acidic strengh increases from H2O to H2Te thus pH decreases and hence the correct of pHs is pH1 > pH2 > pH3 > pH4.
At 25°C, the dissociation con stant of a base, BOH, is 1. 0 x 10-12. The concentration of hydroxyl ions in 0.01 M aqueous solution of the base would be 
Given Kb = 1.0 × 10–12
On calculation, we get, x = 1.0 × 10–5
Now [OH–] =cx
= 0.01 × 10–5
= 1 × 10–7mol L–1
For the reaction 
Which of the following statements is not true ?
First option is incorrect as the value of KP given is wrong. It should have been
The hydrogen ion concentration of a 10–8 M HCl aqueous solution at 298 K (Kw = 10–14) is 
For a solution of 10–8 M HCl [H+] = 10–8 [H+] of water = 10–7
Total [H+] = 10–7 + 10–8 = 10 × 10–8 + 10–8
10–8 (10 + 1) = 11 × 10–8
Which of the following pairs constitutes a buffer?
HNO2 is a weak acid and NaNO2 is salt of that weak acid and strong base (NaOH).
A weak acid, HA, has a Ka of 1.00 × 10–5. If 0.100 mole of this acid dissolved in one litre of water, the percentage of acid dissociated at equilbrium is closest to 
Given Ka = 1.00×10–5, C= 0.100 mol for a weak electrolyte, degree of dissociation
The following equilibrium constants are given:
The equilibrium constant for the oxidation of NH3 by oxygen to give NO is
We have to calculate
For this equation,
Calculate the pOH of a solution at 25°C that contains 1× 10–10 M of hydronium ions, i.e. H3O+.
Given [H3O+] = 1 × 10–10 M at 25º [H3O+] [OH–] = 10–14
∴ pOH = 4
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 ? 
[H3O]+ for a solution having pH = 3 is given by [H3O]+ = 1×10–3 moles/litre
Similarly for solution having pH = 4, [H3O]+ = 1 × 10–4 moles/ litre and for pH=5 [H3O+] = 1×10–5 moles/ litre Let the volume of each solution in mixture be IL, then total volume of mixture solution L = (1 + 1 + 1) L =3L
Total [H3O]+ ion present in mixture solution = (10–3 + 10–4 + 10–5) moles Then [H3O]+ ion concentration of mixture solution
= 0.00037 M = 3.7 ×10–4 M.
If the concentration of OH– ions in the reaction decreased by times, then equilibriumconcentration of Fe3+ will increase by : 
For this reaction Keq. is given by
If (OH–) is decreased by times then forreaction equilibrium constant to remain constant, we have to increase the concentration of [Fe3+] by a factor of 43 i.e 4× 4 × = 64. Thus option (c) is correct answer.
Equimolar solutions of the following were prepared in water separately. Which one of the solutions will record the highest pH ? 
The highest pH will be recorded by the most basic solution. The basic nature of hydroxides of alkaline earth metals increase as we move from Mg to Ba and thus the solution of BaCl2 in water will be most basic and so it will have highest pH.
The dissociation equilibrium of a gas AB2 can be represented as : 
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 :
For the reaction
= x3 [(1–x) can be neglected in denominator
The partial pressure at equilibrium are calculated on the basis of total number of moles at equilibrium.
Total number of moles
= 2 (1–x) + 2x + x = (2 + x)
where P is the total pressure.
Since x is very small so can be neglected in denominator Thus, we get
The values of Kp1 and Kp2 for the reactions
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 :
Given reaction are
Let the total pressure for reaction (i) and (ii) be P1 and P2 respectively, then
At equilibrium (1–α) α α
[Let 1 mole of X dissociate with α as degree of dissociation ]
Total number of moles = 1– α + α + α = (1+α)
Dividing (i) by (ii), we get
i.e. Option (c) is correct answer.
The value of equilibrium constant of the reaction
The equilibrium constant of the reaction
Given : Equilibrium constant (K1) for the reaction
To find equilibrium constant for the following reaction
For this multiply (i) by 2, we get
[Note: When the equation for an equilibrium is multiplied by a factor, the equilibrium constant must be raised to the power equal to the factor]
Now reverse equation (iii), we get
[Note: For a reversible reaction, the equilibrium constant of the backward reaction is inverse of the equilibrium constant for the forward reaction.] Equation (iv) is the same as the required equation (ii), thus K2 for equation (ii) is i.e.
option (b) is correct.
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  would be:
Ka1 , = 1.5 × 10– 5 ....(i)
∴ From (i) and (ii), we find that the equilibrium constant (Ka) for the reaction ,
Which of the following molecules acts as a Lewis acid ?
(CH3)3 B - is an electron deficient, th us behave as a lewis acid.
The ionization constant of ammonium hydroxide is 1.77 × 10–5 at 298 K. Hydrolysis constant of ammonium chloride is: 
Ammonium chloride is a salt of weak base and strong acid. In this case hydrolysis constant Kh can be calculated as
If pH of a saturated solution of Ba (OH)2 is 12, the value of its K(sp) is : 
pH = 12 or pOH = 2
[∴ Concentration of Ba 2+ is half of OH-]
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 . 
In which of the following equilibrium Kc and Kp are not equal? 
Δn = 2 – 1 = + 1
∴ Kc and Kp are not equal.