21555.Phosphorus pentachloride dissociates as follows, in a closed reaction vessel.
PCl5(g) ⇌ PCl3(g) + Cl2(g)
If total pressure at equilibrium of the reaction mixture is P and degree of dissociation of PCl5 is x, the partial pressure of PCl3 will be
$\left(\dfrac{x}{x + 1}\right)P$
$\left(\dfrac{2x}{1 – x}\right)P$
$\left(\dfrac{x}{x – 1}\right)P$
$\left(\dfrac{x}{1 – x}\right)P$
21556.The Ksp for Cr(OH)3 is 1.6 × 10–30. The molar solubility of this compound in water is
1.6 × 10–30/27
$\sqrt[2]{1.6 \times 10^{–30}}$
$\sqrt[4]{1.6 \times 10^{–30}}$
$\sqrt[4]{1.6 \times 10^{–30} / \ 27}$
21557.A vessel at 1000 K contains CO2 with a pressure of 0.5 atm. Some of the CO2 is converted into CO on the addition of graphite. If the total pressure at equilibrium is 0.8 atm, the value of K is
0.18 atm
1.8 atm
3 atm
0.3 atm
21558.An acid HA ionises as
HA ⇌ H+ + A–
The pH of 1.0 M solution is 5. Its dissociation constant would be
1 × 10–5
1 × 10–10
5
5 × 10–8
21559.What is the best description of the change that occurs when Na2O(s) is dissolved in water?
Oxidation number of oxygen increases
Oxidation number of sodium decreases
Oxide ion accepts sharing in a pair of electrons
Oxide ion donates a pair of electrons
21560.0.023 g of sodium metal is reacted with 100 cm3 of water. The pH of the resulting solution is ______.
10
8
9
12
21561.Buffer solutions have constant acidity and alkalinity because
They have large excess of H+ or OH– ions
They have fixed value of pH
These give unionised acid or base on reaction with added acid or alkali
Acids and alkalies in these solutions are shielded from attack by other ions
21562.Four species are listed below
(i) HCO–
3
(ii) H3O+
(iii) HSO–
4
(iv) HSO3F
Which one of the following is the correct sequence of their acid strength?
iv < ii < iii < i
ii < iii < i < iv
i < iii < ii < iv
iii < i < iv < ii
21563.
N2 + 3H2 ⇌ 2NH3 + heat.
What is the effect of the increase of temperature on the equilibrium of the reaction?
equilibrium is shifted to the left
equilibrium is shifted to the right
equilibrium is unaltered
reaction rate does not change
21564.Passing H2S gas into a mixture of Mn2+, Ni2+, Cu2+ and Hg2+ ions in an acidified aqueous solution precipitates
CuS and HgS
MnS and CuS
MnS and NiS
NiS and HgS
21565.In a reversible chemical reaction at equilibrium, if the concentration of any one of the reactants is doubled, then the equilibrium constant will
also be doubled
be halved
remain the same
become one–fourth
21566.In aqueous solution the ionisation constants for carbonic acid are K1 = 4.2 × 10–7 and K2 = 4.8 × 10–11. Select the correct statement for a saturated 0.034 M solution of the carbonic acid.
The concentration of H+ is double that of CO2–
3
3
The concentration of CO2–
3 is 0.034 M
3 is 0.034 M
The concentration of CO2–
3 is greater than that of HCO–
3
3 is greater than that of HCO–
3
The concentrations of H+ and HCO–
3 are approximately equal
3 are approximately equal
21567.H2S is passed into one dm3 of a solution containing 0.1 mole of Zn2+ and 0.01 mole of Cu2+ till the sulphide ion concentration reaches 8.1 × 10–19 moles. Which one of the following statements is true?
[Ksp of ZnS and CuS are 3 × 10–22 and 8 × 10–36 respectively]
[Ksp of ZnS and CuS are 3 × 10–22 and 8 × 10–36 respectively]
Only ZnS precipitates
Both CuS and ZnS precipitate
Only CuS precipitates
No precipitation occurs
21568.The equilibrium constants $\text{K}_{P_{1}}$ and $\text{K}_{P_{1}}$ for the reactions
X ⇌ 2Y and Z ⇌ P + Q
respectively are in the ratio of 1 : 9. If the degree of dissociation of X and Z be equal then the ratio of total pressure at these equilibria is
1 : 36
1 : 1
1 : 3
1 : 9
21569.In 1 L saturated solution of AgCl [KSP (AgCl) = 1.6 × 10–10], 0.1 mol of CuCl [KSP (CuCl) = 1.0 × 10–6] is added. The resultant concentration of Ag+ in the solution is 1.6 × 10–$x$. The value of "$x$" is
7
9
13
15
21570.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?
8
9
10
11
21571.pH of a saturated solution of Ba(OH)2 is 12. The value of solubility product (Ksp) of Ba(OH)2 is
4.0 × 10–6
5.0 × 10–6
3.3 × 10–7
5.0 × 10–7
21573.For the reaction 2HI(g) ⇌ H2(g) + I2(g) – QKJ, the equilibrium constant depends upon
temperature
pressure
catalyst
volume
21574.Three moles of PCl5, three moles of PCl3 and two moles of Cl2 are taken in a closed vessel. If at equilibrium the vessel has 1.5 moles of PCl5, the number of moles of PCl3 present in it is
5
3
6
4.5