Chemical Reactions and Equations Test

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Chemical Reactions and Equations Test - 25

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Weekly Quiz Competition

Question 1
1 / -0

Study the equation given below.

$$2 Al+ (X) {H}_{2}{SO}_{4}\rightarrow Al_2({SO}_4)_{3}+{3H}_{2}$$

In the given equation, what does $$X$$ stand for?

A
2

B
3

C
1

D
5

Solution

It is a double displacement reaction in which Aluminium is a more reactive metal than hydrogen, so hydrogen is being displaced by aluminium.

$$2Al$$+ $$3H_2SO_4$$ $$\rightarrow$$ $$Al_2(SO_4)_3$$ + $$3H_2$$

So $$X$$ stands for 3 and the correct answer is option B.
Question 2
1 / -0

In which reaction do two compounds exchange their ions or radicals mutually to form two new compounds?

A
Displacement reaction.

B
Double displacement reaction.

C
Synthesis reaction.

D
Decomposition reaction.

Solution

Those reactions in which two compounds react by an exchange of ions to form two new compounds are called double displacement reactions. In double replacement reactions, the positive ions and negative ions switch their positions and form two new compounds or products.
example-
$$KOH + HNO_3\rightarrow H_2O + KNO_3$$
$$Na_2S + 2HCI \rightarrow 2NaCl + H_2S$$
Question 3
1 / -0

What happens when copper rod is dipped in iron sulphate solution?

A
A lot of heat will be released

B
The solution becomes blue in colour

C
No reaction takes place

D
The solution becomes pink in colour

Solution

Iron is more reactive than copper. Hence, $$Cu$$ will not displace iron from iron sulphate, hence, no reaction will take place.
Question 4
1 / -0

In the reaction, $$PbO + C \rightarrow Pb + CO$$:

A
PbO is reduced

B
C acts as a oxidizing agent

C
PbO is oxidised

D
This reaction does not represent redox reaction

Solution

Here, carbon oxidizes itself to form $$CO_2$$ and reduces PbO to form Pb. Therefore, $$C$$ acts as a reducing agent. This is a redox reaction.
Question 5
1 / -0

1.0g of $$CaCO_3$$ is taken in a test tube. On heating it over a flame, a colorless gas is evolved. The reaction is called:

A
decomposition reaction

B
displacement reaction

C
combination reaction

D
double displacement reaction

Solution

Calcium carbonate on heating produces calcium oxide and carbon dioxide.
$$CaCO_3\rightarrow CaO+CO_2$$
In the reaction, we can clearly see that there is neither any displacement of atoms nor two reactants are combining to form a product. So, the given reaction is not a displacement or combination reaction. However, in the reaction, the calcium carbonate breaks down into two simple products.
The type of reaction in which a compound breaks down into simple components under suitable conditions is a decomposition reaction.
Question 6
1 / -0

White silver chloride in sunlight turns to :

A
grey

B
yellow

C
green

D
red

Solution

Sunlight carries a good amount of energy, which makes silver chloride (AgCl) decompose in silver (Ag) and chlorine. The metallic silver appears as very small 'flakes', essentially black, so these tiny black spots evenly distributed in the mass of white silver chloride makes it look grey.

$$2AgCl\rightarrow 2Ag+Cl_2$$
Question 7
1 / -0

The reaction between nitrogen and hydrogen to give ammonia is an example of :

A
decomposition reaction

B
combination reaction

C
displacement reaction

D
combustion reaction

Solution

A combination reaction is a reaction in which two or more reactants combine to form a single product.
The reaction between hydrogen gas and nitrogen gsa to give ammonia is as follows.
$$N_2 + 3H_2 \rightarrow 2NH_3$$

Therefore, it is a combination reaction.
Option $$B$$ is correct.
Question 8
1 / -0

$$Zn+H_2SO_4(dil)\rightarrow ZnSO_4+H_2\uparrow$$

The above reaction is:

A
decomposition reaction

B
displacement reaction

C
combination reaction

D
synthesis reaction

Solution

More reactive metal (zinc in this equation) displaces a less reactive element (hydrogen in this equation) from the compound. The given reaction is therefore a displacement reaction. So, option B is correct.

Decomposition reactions are those in which a compound breaks down into simpler substances. Combination reaction is one in which two or more simpler elements combine to form a larger compound. Synthesis reaction is a general term that refers to reactions where two different atoms or molecules interact to form a different molecule or compound, usually to synthesize a new chemical substance.
Question 9
1 / -0

When lead nitrate is heated, it breaks down into lead monoxide, nitrogen dioxide and oxygen.
$$2Pb(NO_3)_2 \rightarrow 2PbO + 4NO_2+O_2$$
The reaction is an example of:

A
combination reaction

B
decomposition reaction

C
double decomposition reaction

D
displacement reaction

Solution

$$2Pb(NO_3)_2 \rightarrow 2PbO + 4NO_2+O_2$$

Here a single reactant is getting decomposed to form different compounds. Hence, it is a decomposition reaction.
Question 10
1 / -0

Which of the following is not a balanced equation?

A
$$Ca(OH)_2+CO_2 \rightarrow CaCO_3 + H_2 O$$

B
$$Fe + CuSO_4 \rightarrow FeSO_4 + Cu$$

C
$$KClO_{4}\overset{\Delta }{\rightarrow}KCl+2O_{2}$$

D
$$Cu+2HNO_3 \rightarrow Cu(NO_3)_2+2NO+H_2O$$

Solution

The number of oxygen atoms on the reactant side is 6 and the number of oxygen atoms on the product side is 9 in option D. Hence, it is an unbalanced equation.

The balanced equation is:
$$3Cu+8HNO_3 \rightarrow 3Cu(NO_3)_2+2NO +4H_2O$$

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Re-Attempt Weekly Quiz Competition

Chemical Reactions and Equations Test - 25

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Chemical Reactions and Equations Test - 25

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SHARING IS CARING

Question 1

2

3

1

5

Solution

Question 2

Displacement reaction.

Double displacement reaction.

Synthesis reaction.

Decomposition reaction.

Solution

Question 3

A lot of heat will be released

The solution becomes blue in colour

No reaction takes place

The solution becomes pink in colour

Solution

Question 4

PbO is reduced

C acts as a oxidizing agent

PbO is oxidised

This reaction does not represent redox reaction

Solution

Question 5

decomposition reaction

displacement reaction

combination reaction

double displacement reaction

Solution

Question 6

grey

yellow

green

red

Solution

Question 7

decomposition reaction

combination reaction

displacement reaction

combustion reaction

Solution

Question 8

decomposition reaction

displacement reaction

combination reaction

synthesis reaction

Solution

Question 9

combination reaction

decomposition reaction

double decomposition reaction

displacement reaction

Solution

Question 10

$$Ca(OH)_2+CO_2 \rightarrow CaCO_3 + H_2 O$$

$$Fe + CuSO_4 \rightarrow FeSO_4 + Cu$$

$$KClO_{4}\overset{\Delta }{\rightarrow}KCl+2O_{2}$$

$$Cu+2HNO_3 \rightarrow Cu(NO_3)_2+2NO+H_2O$$

Solution

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