Chemical Reactions and Equations Test

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Chemical Reactions and Equations Test - 31

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Weekly Quiz Competition

Question 1
1 / -0

Which of the statement is correct about the following reaction?
$$2KClO_3(s)\underset {catalyst}{\xrightarrow {Heat}}2KCl(s)+3O_2(g)$$

A
It is a decomposition reaction and endothermic in nature.

B
It is a combination reaction.

C
It is a decomposition reaction and is accompanied by the evolution of heat.

D
It is a photochemical decomposition reaction and exothermic in nature.

Solution

It is a decomposition reaction as the potassium chlorate compound breaks to form potassium chloride and oxygen. This reaction requires heat as source of energy to break down the compound so it is endothermic in nature.
Question 2
1 / -0

If you pour a few drops of petrol on your palm, it will feel cool as the petrol evaporates. This change is a/an:

A
endothermic reaction

B
exothermic reaction

C
combustion reaction

D
decomposition reaction

Solution

If you pour a few drops of petrol on your palm, it will feel cool as the petrol evaporates. This is an endothermic reaction. Petrol is very volatile in nature. When it evaporates, it absorbs heat energy from the surroundings.
Question 3
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The reaction $$\mathrm{2Na}+\mathrm{Cl}_2\rightarrow \mathrm{2NaCl}$$ is an example of:

A
combination reaction

B
decomposition reaction

C
displacement reaction

D
double displacement reaction

Solution

$$\mathrm{2Na}+\mathrm{Cl}_2\rightarrow \mathrm{2NaCl}$$

In the reaction, two different elements are combining together to form a compound. Therefore, it is a combination reaction. Combination reaction is a reaction in which two or more simple substances combine under suitable conditions to form a single compound.
Question 4
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In the equation, $$Na_2CO_3+xHCl\rightarrow 2NaCl +CO_2+H_2O$$, the value of $$x$$ is:

A
$$1$$

B
$$2$$

C
$$3$$

D
$$4$$

Solution

For balancing any chemical reaction the elements that are mentioned in the reactant should also be mentioned in the product also which is missing in this reaction. i.e., NaCl.

The correct reaction mentioned for balancing should be $$Na_2CO_3 + HCl \longrightarrow NaCl + CO_2 + H_2O$$

After balancing the corrected reaction would be $$Na_2CO_3 + 2HCl \longrightarrow 2NaCl + CO_2 + H_2O$$
Question 5
1 / -0

Corrosion occurs due to:
(a) the action of water on the metal.
(b) the action of air on the metal.
(c) the action of temperature on the metal.

A
a, b

B
b, c

C
a, c

D
all of the above

Solution

The action of air and water gradually eats up the metal. This eating up of metals by the action of air and moisture on their surface is called corrosion.
Question 6
1 / -0

A __________ involves the conversion of reactants into products.

A
physical change

B
chemical reaction

C
Both A and B

D
None

Solution

The chemical reaction involves the conversion of reactants into products.
In this, the constituent atoms of reactants are rearranged to form new substances or products.
Question 7
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Which one of the following does not happen during a chemical reaction?

A
Breaking of old chemical bonds and formation of new chemical bonds

B
Formation of new substance with entirely different properties

C
An atom of one element change into those of another element to form new products

D
A rearrangement of atoms takes place to form new products

Solution

According to Dalton's theory, atoms of the same element are alike in all respect, and atoms of different elements are different.

In a chemical reaction, one substance is converted into another by rearrangement of atoms not by changing elements of one type into another.
Question 8
1 / -0

Which of the following is not a decomposition reaction?

A
$$CaCO_3\rightarrow CaO+CO_2$$

B
$$H_2+Cl_2\rightarrow 2HCl$$

C
$$H_2CO_3\rightarrow H_2O+CO_2$$

D
$$2KClO_3\rightarrow 2KCl+3O_2$$
Question 9
1 / -0

Why is rusting more common in damp areas?

A
Damp areas are deficient of light

B
Damp areas provides air and water

C
Both $$A$$ and $$B$$

D
None of the above

Solution

When iron is attacked by substances around it such as moisture and air, it is said to rust and this process is called rusting.
Damp areas alone supply both the necessary requirements (Air and water) for rust to develop. Therefore, rusting is more common in damp areas.
Question 10
1 / -0

$$Fe_{2}O_{3} + \underline {a} \rightarrow \underline {b} + Al_{2}O_{3}$$
This is an example of displacement reaction. Find a and b:

A
$$a = AlO, b = FeO$$

B
$$a = Al, b = Fe_{2}O_{3}$$

C
$$a = Al_{2}O, b = Fe$$

D
$$a = 2Al, b = 2Fe$$

Solution

In a displacement reaction, one element from a substance is replaced with another element. So, the completed reaction will be:
$$Fe_{2}O_{3} + 2Al \rightarrow 2Fe + Al_{2}O_{3}$$.
Here, iron is replaced by aluminium in ferric oxide.

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Chemical Reactions and Equations Test - 31

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Question 1

It is a decomposition reaction and endothermic in nature.

It is a combination reaction.

It is a decomposition reaction and is accompanied by the evolution of heat.

It is a photochemical decomposition reaction and exothermic in nature.

Solution

Question 2

endothermic reaction

exothermic reaction

combustion reaction

decomposition reaction

Solution

Question 3

combination reaction

decomposition reaction

displacement reaction

double displacement reaction

Solution

Question 4

$$1$$

$$2$$

$$3$$

$$4$$

Solution

Question 5

a, b

b, c

a, c

all of the above

Solution

Question 6

physical change

chemical reaction

Both A and B

None

Solution

Question 7

Breaking of old chemical bonds and formation of new chemical bonds

Formation of new substance with entirely different properties

An atom of one element change into those of another element to form new products

A rearrangement of atoms takes place to form new products

Solution

Question 8

$$CaCO_3\rightarrow CaO+CO_2$$

$$H_2+Cl_2\rightarrow 2HCl$$

$$H_2CO_3\rightarrow H_2O+CO_2$$

$$2KClO_3\rightarrow 2KCl+3O_2$$

Question 9

Damp areas are deficient of light

Damp areas provides air and water

Both $$A$$ and $$B$$

None of the above

Solution

Question 10

$$a = AlO, b = FeO$$

$$a = Al, b = Fe_{2}O_{3}$$

$$a = Al_{2}O, b = Fe$$

$$a = 2Al, b = 2Fe$$

Solution

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