Equilibrium Test

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Equilibrium Test - 27

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Weekly Quiz Competition

Question 1
1 / -0

Of the following which change will shift the reaction towards the product?
$${I}_{2}(g)\rightleftharpoons I(g), \Delta {H}_{r}^{0} (298K)=150kJ$$

A
Increase in concentration of $${I}_{2}$$

B
Decrease in cocentration of $${I}_{2}$$

C
Increase in temperature

D
Increase in total pressure

Solution

The given reaction is endothermic. If we increase the temperature forward reaction will be promoted so that heat is absorbed to decrease the temp.

Hence, option C is correct.
Question 2
1 / -0

A sugar solution contains $$15\mbox{%}$$ sugar by weight. When the solution is heated, $$40\mbox{%}$$ sugar is left in the solution. The amount of water which has disappeared is

A
$$0.0625\space g$$

B
$$62.5\space g$$

C
$$0.625\space g$$

D
$$6.25\space g$$

Solution

Let the mass of the solution = 100 g
Mass of sugar = 15 g
Mass of water = 100 - 15 = 85 g
On heating some water is disappeared and let the new amount of solution be $$X$$ g, which contains $$40\mbox{%}$$ sugar equal to $$15g$$
$$x\times\displaystyle\frac{40}{100} = 15$$
$$x = 37.5g$$
After heating mass of the solution is $$37.5g$$
Mass of water = mass of solution - mass of sugar = 37.5 - 15 = 22.5 g
Amount of water disappeared on heating = 85 - 22.5 = 62.5g
Question 3
1 / -0

The product of molar concentrations of hydrogen ions and hydroxide ions in a $$0.01 M$$ aqueous solution of sodium chloride is known as

A
Hydrolysis constant of salt

B
Dissociation constant of acid

C
Dissociation constant of base

D
Ionic product of water

Solution

Sodium chloride is a salt of strong base $$NaOH$$ and strong acid $$HCl$$. In its aqueous solution, following equilibrium is observed.
$$NaCl+{ H }_{ 2 }O\rightleftharpoons { Na }^{ + }+{ Cl }^{ - }+{ H }_{ 2 }O$$
Hence, no hydrolysis takes place in this case, and the solution remains neutral. Thus, here the product of molar concentrations of hydrogen ions and hydroxide ions is ionic product of water.
Question 4
1 / -0

If the dissociation constants of two substances are $${K}_{1}$$ and $${K}_{2}$$ respectively, then the ratio of degree of dissociation for a given concentration, is given by

A
$$\cfrac{{K}_{1}}{{K}_{2}}$$

B
$$\sqrt{\cfrac{{K}_{1}}{{K}_{2}}}$$

C
$$\cfrac { { \left( { K }_{ 1 } \right) }^{ 2 } }{ { K }_{ 2 } } $$

D
$$\cfrac { { K }_{ 1 }.{ K }_{ 2 } }{ { K }_{ 2 } } $$

Solution

From OStwald dilution formula
$$K={\alpha}^{2}C$$
where $$K$$ is dissociation constant and $$\alpha$$ is degree of dissociation or ionisation
$$\cfrac{{K}_{1}}{{K}_{2}}=\cfrac{{\alpha}_{1}^{2}}{{\alpha}_{2}^{2}}$$
$$\cfrac{{\alpha}_{1}}{{\alpha}_{2}}=\sqrt {\cfrac{{K}_{1}}{{K}_{2}}}$$
Question 5
1 / -0

The chemical equilibrium of reversible reaction is not influenced by:

A
pressure

B
catalyst

C
concentration of the reactants

D
temperature

Solution

Chemical equilibrium of reversible reaction is not influenced by the catalyst. Catalyst decreases the activation barrier for a reaction so the reaction proceeds fast. In the presence of the catalyst, the equilibrium reaches faster but it doesn't affect the thermodynamic properties.
Question 6
1 / -0

A chemist interested in the reactivity of iodine concentrates his study on the decomposition of gaseous hydrogen iodide (Reaction 1).
$$\displaystyle 2HI\left( g \right) \leftrightharpoons { H }_{ 2 }\left( g \right) +{ I }_{ 2 }\left( g \right) $$
An increase in pressure in Reaction 1 would:

A
produce more $$I_2 (g)$$

B
produce more $$H_2(g)$$

C
not affect the system

D
drive it to the right

Solution

The given reaction is:-
$$2HI\left( g \right) \rightleftharpoons { H }_{ 2 }\left( g \right) +{ I }_{ 2 }\left( g \right) $$
Since, the no. of moles of gaseous species on both sides i.e. on reactants and products side are same, so, increase of pressure in this reaction do not affect the reaction.
Question 7
1 / -0

In III group precipitation, $$NH_4Cl$$ is added before adding $$NH_4OH$$ to.

A
Decrease conc. of $$OH^-$$

B
Prevent interference of $$PO^{3-}_4$$

C
Increase conc. of $$Cl^-$$

D
Increase conc. of $$OH^-$$ ion.

Solution

The common ion effect is responsible for the reduction in the solubility of an ionic precipitate when a soluble compound containing one of the ions of the precipitate is added to the solution in equilibrium with the precipitate.

Due to Common ion effect, the concentration of $${OH}^-$$ decreases when $$NH_4Cl$$ is added to $$NH_4OH$$
Question 8
1 / -0

A buffer solution:

A
rapidly changes pH due to addition of an acid.

B
resists changes in pH.

C
does not change pH at all.

D
changes pH only with the addition of a strong base.

Solution

The solution of buffer resists changes in $$pH$$.

A buffer solution is defined as a solution which resists drastic changes in $$pH$$ upon the addition of a small amount of either an acid or a base.

Hence, te correct option is $$\text{B}$$
Question 9
1 / -0

Which of the following pairs of species could be a buffer?

A
H$$^+$$ and Cl$$^-$$

B
H$$_2$$CO$$_3$$ and HCO$$_3^-$$

C
Na$$^+$$ and NO$$_3^-$$

D
Na$$^+$$ and OH$$^-$$

E
HNO$$_3$$ and NO$$_3^-$$

Solution

$$\displaystyle H_2CO_3 + HCO_3^-$$ constitutes a buffer solution. An acidic buffer solution is a mixture of weak acid (such as carbonic acid) and its salt (bicarbonate) with strong base (such as NaOH or KOH).

Hence option B is correct.
Question 10
1 / -0

Which of the following is a correct statement?

A
The number of positive ions in solution equals the number of negative ions.

B
The total positive charge and total negative charge are equal in the solution.

C
The positive ions are known as cathodes.

D
The positive ions are known as anions.

E
None of the above

Solution

The total positive charge and total negative charge are equal in the solution. Due to this, the solution is electrically neutral.

For example, a solution of NaCl in water contains equal number of $$\displaystyle Na^+$$ ions and $$\displaystyle Cl^-$$ ions.

Hence option B is correct.

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Equilibrium Test - 27

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Equilibrium Test - 27

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Question 1

Increase in concentration of $${I}_{2}$$

Decrease in cocentration of $${I}_{2}$$

Increase in temperature

Increase in total pressure

Solution

Question 2

$$0.0625\space g$$

$$62.5\space g$$

$$0.625\space g$$

$$6.25\space g$$

Solution

Question 3

Hydrolysis constant of salt

Dissociation constant of acid

Dissociation constant of base

Ionic product of water

Solution

Question 4

$$\cfrac{{K}_{1}}{{K}_{2}}$$

$$\sqrt{\cfrac{{K}_{1}}{{K}_{2}}}$$

$$\cfrac { { \left( { K }_{ 1 } \right) }^{ 2 } }{ { K }_{ 2 } } $$

$$\cfrac { { K }_{ 1 }.{ K }_{ 2 } }{ { K }_{ 2 } } $$

Solution

Question 5

pressure

catalyst

concentration of the reactants

temperature

Solution

Question 6

produce more $$I_2 (g)$$

produce more $$H_2(g)$$

not affect the system

drive it to the right

Solution

Question 7

Decrease conc. of $$OH^-$$

Prevent interference of $$PO^{3-}_4$$

Increase conc. of $$Cl^-$$

Increase conc. of $$OH^-$$ ion.

Solution

Question 8

rapidly changes pH due to addition of an acid.

resists changes in pH.

does not change pH at all.

changes pH only with the addition of a strong base.

Solution

Question 9

H$$^+$$ and Cl$$^-$$

H$$_2$$CO$$_3$$ and HCO$$_3^-$$

Na$$^+$$ and NO$$_3^-$$

Na$$^+$$ and OH$$^-$$

HNO$$_3$$ and NO$$_3^-$$

Solution

Question 10

The number of positive ions in solution equals the number of negative ions.

The total positive charge and total negative charge are equal in the solution.

The positive ions are known as cathodes.

The positive ions are known as anions.

None of the above

Solution

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