Equilibrium Test

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Equilibrium Test - 7

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Weekly Quiz Competition

Question 1
4 / -1

The equilibrium which is not affected by volume change at constant temperature is

A
H₂(g) +I₂(g)2HI(g)

B
N₂ (g) + 3H₂(g) 2NH₃(g)

C
N₂O₄(g) 2NO₂(g)

D
2NO(g) +O₂(g) 2NO₂(g)

Solution

As the number of moles of reactants and products is the same. Hence, they both will occupy equal volume at the same temperature.
Therefore, the reaction A i.e., H2 (g) +I2 (g) ⇌ 2HI (g) is not affected by change in pressure and volume.
Question 2
4 / -1

In each of the following equilibria, pressure is made four times after equilibrium is set up. In which case yield of the product(s) is maximum?

A
N₂O₄ (g)2NO₂(g)

B
C(s) + H₂O(g) CO(g) +H₂(g)

C
N₂(g) + 3H₂(g)2NH₃(g)

D
2Fe(s) +3H₂O (g) Fe₂O₃(s) + 3H₂(g)
Question 3
4 / -1

The binding of oxygen by haemoglobin (Hb) forming (HbO₂), is partially regulated by the concentration of H₃O + and dissolved CO₂ in blood.
Release of O₂ is favoured when there is

A
production of CO₂ during excertion

B
production of lactic acid during excertion

C
Both (a) and (b) take place

D
None of (a) and (b) takes place

Solution

During exercise muscle need energy hence consume more oxygen and produce more CO₂ and lactic acid gets accumulated as well. According to bohr's effect oxygen binding affinity is inversely proportional to CO₂ concentration and acidity. Thus favours the dissociation or release of O₂.
Question 4
4 / -1

Aerated water contains CO₂ dissolved in water
CO₂(g) + H₂O(l) H₂CO₃(aq)

Variation of solubility (s) with pressure (p) is shown by

A

B

C

D

Solution

Pressure increase solubility also increase in accordance with the Henry's law and option B is the closest to this. Hence B is correct.
Question 5
4 / -1

Variation of log K_p with temperature. 1/T is given by for the equilibrium.
NH₄HS (s) NH₃(g) + H₂S
Q. The equilibrium is displaced in forward side on

A
increasing temperature and decreasing pressure

B
increasing temperature and pressure both

C
decreasing temperature and pressure both

D
decreasing temperature and increasing pressure

Solution

The correct answer is Option A.
When ammonia is added after equilibrium is established, the partial pressure of ammonia will increase.When the temperature of an endothermic reaction is increased, the equilibrium will shift in the forward direction so that the heat is absorbed which will nullify the effect of increased temperature. Hence, the partial pressure of ammonia will increase.When the volume of the flask is increased, the pressure will decrease.
Question 6
4 / -1

In the following equilibrium AB A⁺ + B^-
AB is 10% dissociated, when [AB] = 1M
Q. What is per cent dissociation if 1 M AB is dissociated in the presence of 1 M A⁺?

A
5.2%

B
6.0%

C
1.1%

D
10.0%

Solution

The correct answer is option C
Let initially
AB = 1M
AB = A⁺ + B^-
⇒1 - 0.1

K should remain same
AB ⇌ A⁺ + B^-
1-x
Question 7
4 / -1

When hydrochloric acid is added to cobalt (II) nitrate solution at room temperature, the following reaction takes place
Q. The solution is blue at room temperature. However, it turns pink when cooled in a freezing mixture. Based upon this information, which of the following expression is correct for the forward reaction?

A
ΔH > 0

B
ΔH < 0

C
ΔH = 0

D
The sign of ΔH can’t be predicted based on the given information

Solution

According to the given information, the solution turns pink when cooled in freezing mixture. So, the equilibrium has shifted in backward direction. So we can say that the reaction is endothermic and ∆H for the reaction is greater than zero. This is because, endothermic reactions have ∆H > 0 and they proceed in reverse direction.
Question 8
4 / -1

Consider the following equilibrium in a closed container
N₂O₄ (g)2NO₂(g)
At a fixed temperature, the volume of a reaction container is halved. For this change, which of the following statements holds true regarding the equilibrium constant (K_p) and degree of dissociation (α) ?

A
Neither K_p nor α change

B
Both K_p and α change

C
K_p changes but α does not change

D
K_p does not change but α changes

Solution

We know that K_p depends only on Temperature. As the temp. remains constant , K_p also remains constant.
α depends on the concentration of the reactant
So as the volume of the reaction container is halved, α also changes
So option d is correct.
Question 9
4 / -1

Once the equilibrium is reached under given condition:

A
Cone, remains the same in spite of the change in temperature

B
Cone, of all the substances presents do not change

C
Cone, of reactants remairfs same

D
Cone, of products remains same

Solution

In a chemical reaction, chemical equilibrium is the state in which the forward reaction rate and the reverse reaction rate are equal. The result of this equilibrium is that the concentrations of the reactants and the products do not change. However, just because concentrations aren’t changing does not mean that all chemical reaction has ceased. Just the opposite is true; chemical equilibrium is a dynamic state in which reactants are being converted into products at all times, but at the exact rate that products are being converted back into reactants. The result of such a situation is analogous to a bridge between two cities, where the rate of cars going over the bridge in each direction is exactly equal. The result is that the net number of cars on either side of the bridge does not change.
Question 10
4 / -1

Which one of the following molecular hydrides acts as a Lewis acid?

A
CH₄

B
NH₃

C
H₂O

D
B₂H₆

Solution

B₂H₆ is an electron deficient species. Soit will act as Lewis acid.
Question 11
4 / -1

Which of the following will produce a buffer solution when mixed in equal volumes ?

A
0.1 mol dm^–3 NH₄OH and 0.1 mol dm^–3 HCl

B
0.05 mol dm^–3 NH₄OH and 0.1 mol dm^–3 HCl

C
0.1 mol dm^–3 NH₄OH and 0.05 mol dm^–3 HCl

D
0.1 mol dm^–3CH₄COONa and 0.1 mol dm^–3 NaOH

Solution

For a buffer, we need to have a weak base/acid and its salt. Here, we have a weak base and so we will need its salt. In option c, concentration of strong acid is less than base. So we will have both a weak base and its salt. Therefore, only option c gives us a buffer solution.
Question 12
4 / -1

Acidic strength is in order

A
H₂O < CH₃COOH < HF < NH₃

B
NH₃ < H₂O < CH₃COOH < HF

C
HF < CH₃COOH < H₂O < NH₃

D
H₂O < NH₃ < HF < CH₃COOH

Solution

When we move from left to right, electronegativity of central atom increases. Due to this nature, central atom has more tendency to break its bond with H and acquire negative charge. So, while moving from left to right, acidic strength increase.
Question 13
4 / -1

Which of the following is more acidic? A solution with pH 5 or a solution with pH 3

A
solution with pH 5

B
solution with pH 3

C
both are equally acidic

D
cannot be predicted from pH values

Solution

We know that pH equals to - log[H⁺] or the value of pH is inversely proportional to the concentration of H⁺. So more the value of pH, less the solution be acidic.
Question 14
4 / -1

Which one of the following is the approximate pH of 0.01 M solution of NaOH at 298 k?

A
10^-2

B
2.5

C
12

D
2

Solution

First off, since NaOH is a strong base, it will dissociate completely into Na+ and OH-. Thus, we know that we have 0.01 M OH-.

However, we do not know anything about the concentration of H+. Fortunately, we do not need to, as pH + pOH = 14. So, if we find pOH, we can solve for pH. p is a mathematical function equivalent to -log. So, pH actually means -log[H+] (Note that brackets indicate concentration of).

pOH = -log 0.01M OH-

pOH = 2

pH + 2 = 14

pH = 12

This result makes sense, since a solution of strong base should have a high pH.
Question 15
4 / -1

Which one of the following is correct for a solution in which [H⁺] = 10^-8 M.

A
6, basic

B
-6, basic

C
8, basic

D
-8, neutral
Question 16
4 / -1

Which one of the following is a wrong derivation?

A
K_w = K_a x K_b

B
K_w = K_h/K_a

C
K_w = K_a x K_bXK_h

D
K_w = [OH^–][H⁺]
Question 17
4 / -1

Value of pH is determined by

A
pH electrode

B
pH detector

C
pH balancer

D
pH spectrometer

Solution

The pH measurement electrode is made of special glass which, due to its surface properties, is particularly sensitive to hydrogen ions. The pH measurement electrode is filled with a buffer solution which has a pH value of 7.
Question 18
4 / -1

For the reaction,
2SO₂ (g) + O₂ (g)2SO₃ (g) + 188.3 KJ

the number of moles of SO₃ formed is increased if

A
temperature is increased at constant V

B
inert gas is added to the mixture

C
O₂ is removed from the mixture

D
volume of the reaction flask is decreased

Solution

Volume decreased
i.e p increased
no.of moles reactant more
Question 19
4 / -1

We know that the relationship between K_c and K_p is K_p = K_c (RT)^Δn
What would be the value of Δn for the reaction NH₄Cl (s) ⇔ NH₃ (g) + HCl (g)

A
1

B
0.5

C
1.5

D
2

Solution