Chemical Reactions and Equations Test

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Chemical Reactions and Equations Test - 28

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Weekly Quiz Competition

Question 1
1 / -0

The reaction between carbon and oxygen can be represented as;
$$C_{(s)} + O_{2(g)} \rightarrow CO_{2(g)} + heat$$
In which of the following type(s), the above reaction can be classified?
I. Combustion reaction
II. Displacement reaction
III. Endothermic reaction
IV. Combination reaction

A
(I) and (III)

B
(I), (Ill) and (IV)

C
(I) and (IV)

D
(1) only

Solution

The reaction $$C + O_2 \rightarrow CO_2$$ is a chemical reaction.
It is an exothermic reaction and also oxidation. Exothermic because it releases heat and oxidation because the carbon atom forms a covalent bond with the oxygen.

It is a combustion reaction because combustion is the burning of a compound with evolution of a considerable amount of heat energy. In this reaction, $$C$$ (carbon) is burnt in $$O_2$$ ( Oxygen) and release heat energy. Therefore, this reaction is a combination reaction and a combustion reaction. Thus, option " C" is correct.
Question 2
1 / -0

Write the balanced chemical reaction for the conversion of sulphur to sulphuric acid.

A
$$S+ \underset {(hot\ and\ conc.)} {HNO _3 } \rightarrow { H }_{ 2 }{ SO }_{ 4 }+{ 2H }_{ 2 }O+{ NO }_{ 2 }$$

B
$$S+ \underset {(hot\ and\ conc.)} {6{ HNO }_{ 3 }}\rightarrow { H }_{ 2 }{ SO }_{ 4 }+{ 2H }_{ 2 }O+{ 6NO }_{ 2 }$$

C
$$2S+\underset {(hot\ and\ conc.)} {6{ HNO }_{ 3 }} \rightarrow 2{ H }_{ 2 }{ SO }_{ 4 }+{ 2H }_{ 2 }O+{ 6NO }_{ 2 }$$

D
$$2S+\underset {(hot\ and\ conc.)} {3{ HNO }_{ 3 }}\rightarrow 2{ H }_{ 2 }{ SO }_{ 4 }+{ 2H }_{ 2 }O+{ 3NO }_{ 2 }$$

Solution

Sulphur reacts with nitric acid to form sulphuric acid.

$$S+ \underset {(hot\ and\ conc)} {6{ HNO }_{ 3 }}\rightarrow { H }_{ 2 }{ SO }_{ 4 }+{ 2H }_{ 2 }O+{ 6NO }_{ 2 }$$

Hence, option B is correct.
Question 3
1 / -0

Which of the following pair will give displacement reaction?

A
$$NaCl$$ solution and copper metal

B
$$MgCl_2$$ solution and aluminium metal

C
$$FeSO_4$$ solution and silver metal

D
$$ AgNO_3$$ solution and copper metal

Solution

Copper metal is more reactive than silver nitrate so it can displace silver and can form copper nitrate.
$$2{ AgNO }_{ 3 }+Cu\rightarrow { Cu\left( { NO }_{ 3 } \right) }_{ 2 }+2Ag$$
Question 4
1 / -0

Which of the following is the correctly balanced chemical equation?

A
$$Ca(OH)_2$$ + $$HF$$ $$\longrightarrow$$ $$2H_2O$$ + $$CaF_2$$

B
$$Ca(OH)_2$$ + $$HF$$ $$\longrightarrow$$ $$2H_2O$$ + $$2CaF_2$$

C
$$Ca(OH)_2$$ + $$2HF$$ $$\longrightarrow$$ $$2H_2O$$ + $$2CaF_2$$

D
$$Ca(OH)_2$$ + $$2HF$$ $$\longrightarrow$$ $$2H_2O$$ + $$CaF_2$$

Solution

In the balanced equation, number of each atoms on reactant and product side are equal.

$$Ca(OH)_2$$ + $$2HF$$ $$\longrightarrow$$ $$2H_2O$$ + $$CaF_2$$

$$\text {Atoms On reactant side (LHS) On product side (RHS)}$$
$$\text{ Ca 1 1 }$$
$$\text { O 2 2} $$
$$\text { H 4 4}$$
$$\text { F 2 2}$$
Here, all the atoms on reactant and product side are same, hence, option $$D$$ is correct.
Question 5
1 / -0

Select the wrong option about rancidity.

A
Aerial oxidation of fats

B
Aerial oxidation of oils

C
Oils left in refrigerator gets rancid

D
Chips exposed to air gets rancid

Solution

Some oils may become cloudy when refrigerated, but this disappears when they return to room temperature, and this is no reflection on the oil's wholesomeness. Oils will go rancid if they are mistreated or stored in the wrong way. Rancidity occurs when the oil reacts with oxygen, and aside from giving foods an off-taste, oxidized oil does represent a health risk if you consume it.
Rancidity is the spoilage of fatty acid content of food due to which the food gives bad smell and taste.
Question 6
1 / -0

What do you observe when $$H_2S$$ gas is passed through cadmium chloride solution? Name the type of reaction:

A
Synthesis

B
Displacement

C
Double displacement

D
Neutralisation

Solution

When $$H_2S$$ gas i.e. hydrogen sulphide gas is passed through cadmium chloride solution, yellow colored precipitate of cadmium sulphide (CdS) is formed and aqueous hydrochloric acid (HCl) is formed.
$$H_2S(g) + CdCl_2(aq) \rightarrow CdS(s) + 2HCl(aq)$$
Question 7
1 / -0

$$CuO(s) + H_2(g) \rightarrow Cu(s) + H_2O(l)$$
In this reaction, _______ is reduced.

A
copper oxide

B
copper

C
hydrogen

D
water

Solution

$$CuO(s) + H_2(g) \rightarrow Cu(s) + H_2O(l)$$
In this reaction hydrogen gains oxygen and forms water, hence it is oxidised. On the other hand copper oxide loses oxygen and hence reduced.
Question 8
1 / -0

Write the balanced chemical reaction for the reaction of magnesium with hot water.

A
$$2Mg + 3H_2O \rightarrow 2MgOH + 3H_2$$

B
$$Mg + 2H_2O \rightarrow Mg(OH)_2 + H_2$$

C
$$2Mg + 3H_2O \rightarrow 3MgOH + 3H_2$$

D
$$Mg + 3H_2O \rightarrow 2MgOH + 3H_2$$

Solution

Magnesium reacts with hot water to form magnesium hydroxide and hydrogen.
$$Mg + 2H_2O \rightarrow Mg(OH)_2 + H_2 $$
Question 9
1 / -0

Formation of nitric oxide from nitrogen and oxygen is a ______ reaction.

A
combination

B
displacement

C
calcination

D
roasting

Solution

A combination reaction is a reaction where two or more elements or compounds (reactants) combine together to form a single compound (product).
$$N_2+O_2 \rightarrow 2NO$$
Question 10
1 / -0

Breaking of lead bromide into lead and bromine is an example of _____.

A
decomposition reaction

B
synthesis reaction

C
displacement reaction

D
neutralisation reaction

Solution

Decomposition reaction - separation of a substance into two or more substances that may differ from each other and from the original substance.
$$PbBr_2 \rightarrow Pb+Br_2$$

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Chemical Reactions and Equations Test - 28

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Question 1

(I) and (III)

(I), (Ill) and (IV)

(I) and (IV)

(1) only

Solution

Question 2

$$S+ \underset {(hot\ and\ conc.)} {HNO _3 } \rightarrow { H }_{ 2 }{ SO }_{ 4 }+{ 2H }_{ 2 }O+{ NO }_{ 2 }$$

$$S+ \underset {(hot\ and\ conc.)} {6{ HNO }_{ 3 }}\rightarrow { H }_{ 2 }{ SO }_{ 4 }+{ 2H }_{ 2 }O+{ 6NO }_{ 2 }$$

$$2S+\underset {(hot\ and\ conc.)} {6{ HNO }_{ 3 }} \rightarrow 2{ H }_{ 2 }{ SO }_{ 4 }+{ 2H }_{ 2 }O+{ 6NO }_{ 2 }$$

$$2S+\underset {(hot\ and\ conc.)} {3{ HNO }_{ 3 }}\rightarrow 2{ H }_{ 2 }{ SO }_{ 4 }+{ 2H }_{ 2 }O+{ 3NO }_{ 2 }$$

Solution

Question 3

$$NaCl$$ solution and copper metal

$$MgCl_2$$ solution and aluminium metal

$$FeSO_4$$ solution and silver metal

$$ AgNO_3$$ solution and copper metal

Solution

Question 4

$$Ca(OH)_2$$ + $$HF$$ $$\longrightarrow$$ $$2H_2O$$ + $$CaF_2$$

$$Ca(OH)_2$$ + $$HF$$ $$\longrightarrow$$ $$2H_2O$$ + $$2CaF_2$$

$$Ca(OH)_2$$ + $$2HF$$ $$\longrightarrow$$ $$2H_2O$$ + $$2CaF_2$$

$$Ca(OH)_2$$ + $$2HF$$ $$\longrightarrow$$ $$2H_2O$$ + $$CaF_2$$

Solution

Question 5

Aerial oxidation of fats

Aerial oxidation of oils

Oils left in refrigerator gets rancid

Chips exposed to air gets rancid

Solution

Question 6

Synthesis

Displacement

Double displacement

Neutralisation

Solution

Question 7

copper oxide

copper

hydrogen

water

Solution

Question 8

$$2Mg + 3H_2O \rightarrow 2MgOH + 3H_2$$

$$Mg + 2H_2O \rightarrow Mg(OH)_2 + H_2$$

$$2Mg + 3H_2O \rightarrow 3MgOH + 3H_2$$

$$Mg + 3H_2O \rightarrow 2MgOH + 3H_2$$

Solution

Question 9

combination

displacement

calcination

roasting

Solution

Question 10

decomposition reaction

synthesis reaction

displacement reaction

neutralisation reaction

Solution

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