Class 10 Science Chemical Reactions and Equations questions

Q 21 :
A dilute ferrous sulphate solution was gradually added to the beaker containing acidified potassium permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?

$K M n O_{4}$ is an oxidising agent, it oxidises $F e S O_{4}$ .
$F e S O_{4}$ acts as an oxidising agent and oxidises $K M n O_{4}$
The colour disappears due to dilution; no reaction is involved
$K M n O_{4}$ is an unstable compound and decomposes in presence of $F e S O_{4}$ to a colourless compound

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(1)

In this reaction, potassium permanganate $(K M n O_{4})$ is an oxidising agent. It oxidises ferrous sulphate to ferric sulphate in the presence of dilute $H_{2} S O_{4}$

$2 K M n O_{4} + 10 F e S O_{4} + 8 H_{2} S O_{4} \to K_{2} S O_{4} + 2 M n S O_{4} + 5 F e_{2} {(S O_{4})}_{3} + 8 H_{2} O$

The solution is coloured purple because of the KMnO?, and it eventually disappears when all the KMnO? in the solution is used.:

Q 22 :
Which of the following gases can be used for storage of fresh sample of an oil for a long time?

Carbon dioxide
Nitrogen
Hydrogen
Helium

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(4)

Helium can be used to store the fresh samples of an oil for a long time since it is an inert gas and will not react with the sample of the food, keeping its quality intact as such.

Q 23 :
Shashank was asked to carry out a displacement reaction which would show the following:

(i) Formation of colourless solution
(ii) Black deposits

The reactants he should use are:

Fe(s) and $A l_{2} {(S O_{4})}_{3}$ (aq)
Al(s) and $F e S O_{4}$ (aq)
$Z n (s) a n d C u S O_{4} (a q)$
$F e (s) a n d Z n S O_{4} (a q)$

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(2)

When aluminium metal is added to ferrous sulphate $(F e S O_{4})$ solution, the green colour of ferrous sulphate solution disappears and a colourless solution is formed due to the formation of aluminium sulphate solution, and greyish-black iron gets deposited.

$\underset{G r e e n s o l u t i o n}{3 F e S O_{4}} (a q) + 2 A l (s) ⟶ \underset{G r e y i s h b l a c k d e p o s i t}{3 F e (s)} + \underset{C o l o u r l e s s s o l u t i o n}{A l_{2} {(S O_{4} )}_{3} (a q)}$

Q 24 :
The oxidation reaction which produces heat and light is called:

Endothermic
Photochemical
Exothermic
Combustion

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(4)

A combustion reaction is a kind of chemical reaction in which a reaction between any combustible substance and an oxidiser takes place in order to form an oxidised product accompanied by the evolution of heat and light during the reaction.

Q 25 :
Heating of ferrous sulphate is a type of:

Decomposition reaction
Combination reaction
Displacement reaction
All of the above

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(1)

A decomposition reaction is a reaction in which a compound breaks down into two or more simpler substances. Most decomposition reactions require an input of energy in the form of heat, light, or electricity.

The heating of ferrous sulphate is a decomposition and an endothermic reaction because it involves absorption of heat to form ferric oxide $(F e_{2} O_{3})$ , sulphur dioxide ( $S O_{2}$ ), and sulphur trioxide $(S O_{3})$ .

The equation for this reaction can be written as:
$2 F e S O_{4} (s) \overset{h e a t}{\to} F e_{2} O_{3} (s) + S O_{2} (g) + S O_{3} (g)$

Q 26 :
To balance $A l {(O H)}_{3} + H N O_{3} ⟶ A l {(N O_{3})}_{3} + H_{2} O$ , number of $H N O_{3}$ molecules required will be:

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4
3
8

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(3)

Three molecules of $H N O_{3}$ are required to balance the given chemical reaction and to satisfy the law of conservation of mass.

$A l {(O H)}_{3} + 3 H N O_{3} ⟶ A l {(N O_{3})}_{3} + 3 H_{2} O$

Q 27 :
Which metal is displaced when lead is put in the solution of copper chloride?

Lead
Copper
Chlorine
All of these

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(2)

Copper will be displaced from the solution since it is less reactive than lead. Lead will displace copper from its salt solution because it is more reactive than copper.

Q 28 :
What is the name of the process where fatty foods become rancid?

Corrosion
Oxidation
Reduction
Hydrogenation

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(2)

Fatty foods become rancid due to the process of oxidation. Food turns rancid when the fats and oils within them get oxidised and the taste and smell of the food changes. It is produced by aerial oxidation of unsaturated fat present in foods and other products, marked by unpleasant odour or flavour.

Q 29 :
Rancidity can be prevented by:

adding antioxidants
storing food away from light
keeping food in refrigerator
all of the above

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(4)

Rancidity can be prevented by packing fat- and oil-containing foods in nitrogen gas. It can be retarded by keeping food in a refrigerator. It can also be retarded by storing food in air-tight containers and away from light in order to prevent their decomposition

Q 30 :
Assertion: Gold and silver do not corrode in moist air.
Reason: It is because they have low reactivity.

Both assertion and reason are correct and reason is the correct explanation of assertion.
Both assertion and reason are correct, but reason is not the correct explanation of assertion
Assertion is true, but reason is false.
Assertion is false, but reason is true.

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(1)

Gold and silver lie very low in the activity series of metals. Thus, they have low reactivity and hence do not corrode in moist air. Therefore, both assertion and reason are correct and reason is the correct explanation of the assertion.

Topic Question Set

Q 21 :
A dilute ferrous sulphate solution was gradually added to the beaker containing acidified potassium permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?

Q 22 :
Which of the following gases can be used for storage of fresh sample of an oil for a long time?

Q 23 :
Shashank was asked to carry out a displacement reaction which would show the following:

(i) Formation of colourless solution
(ii) Black deposits

The reactants he should use are:

Q 24 :
The oxidation reaction which produces heat and light is called:

Q 25 :
Heating of ferrous sulphate is a type of:

Q 26 :
To balance $A l {(O H)}_{3} + H N O_{3} ⟶ A l {(N O_{3})}_{3} + H_{2} O$ , number of $H N O_{3}$ molecules required will be:

Q 27 :
Which metal is displaced when lead is put in the solution of copper chloride?

Q 28 :
What is the name of the process where fatty foods become rancid?

Q 29 :
Rancidity can be prevented by:

Q 30 :
Assertion: Gold and silver do not corrode in moist air.
Reason: It is because they have low reactivity.

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Topic Question Set

Q 21 : A dilute ferrous sulphate solution was gradually added to the beaker containing acidified potassium permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?

Q 22 : Which of the following gases can be used for storage of fresh sample of an oil for a long time?

Q 23 : Shashank was asked to carry out a displacement reaction which would show the following: (i) Formation of colourless solution (ii) Black deposits The reactants he should use are:

Q 24 : The oxidation reaction which produces heat and light is called:

Q 25 : Heating of ferrous sulphate is a type of:

Q 26 : To balance Al(OH)3 + HNO3 ⟶ Al(NO3)3 + H2O, number of HNO3 molecules required will be:

Q 27 : Which metal is displaced when lead is put in the solution of copper chloride?

Q 28 : What is the name of the process where fatty foods become rancid?

Q 29 : Rancidity can be prevented by:

Q 30 : Assertion: Gold and silver do not corrode in moist air. Reason: It is because they have low reactivity.

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Q 21 :
A dilute ferrous sulphate solution was gradually added to the beaker containing acidified potassium permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?

Q 22 :
Which of the following gases can be used for storage of fresh sample of an oil for a long time?

Q 23 :
Shashank was asked to carry out a displacement reaction which would show the following:

(i) Formation of colourless solution
(ii) Black deposits

The reactants he should use are:

Q 24 :
The oxidation reaction which produces heat and light is called:

Q 25 :
Heating of ferrous sulphate is a type of:

Q 26 :
To balance $A l {(O H)}_{3} + H N O_{3} ⟶ A l {(N O_{3})}_{3} + H_{2} O$ , number of $H N O_{3}$ molecules required will be:

Q 27 :
Which metal is displaced when lead is put in the solution of copper chloride?

Q 28 :
What is the name of the process where fatty foods become rancid?

Q 29 :
Rancidity can be prevented by:

Q 30 :
Assertion: Gold and silver do not corrode in moist air.
Reason: It is because they have low reactivity.