10th Grade > Chemistry
CHEMICAL REACTIONS AND EQUATIONS MCQs
Total Questions : 51
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Answer: Option D. -> 2K(s)+2H2O(l)→2KOH(aq)+H2(g)
:
D
Potassium reacts with water to form potassium hydroxide along with hydrogen. The chemical equation for this reactionis given below:
K(s)+H2O(l)→KOH(aq)+H2(g)
We can see that:
Reactant
Product
Elements Symbol
No. of atoms
Elements Symbol
No. of atoms
K
1
K
1
H
2
H
3
O
1
O
1
Now in order to balance the equation the number of atoms on both reactants and the products side should be equal. By applying hit and trialmethod the balanced equation of the given reaction is:
2K(s)+2H2O(l)→2KOH(aq)+H2(g)
:
D
Potassium reacts with water to form potassium hydroxide along with hydrogen. The chemical equation for this reactionis given below:
K(s)+H2O(l)→KOH(aq)+H2(g)
We can see that:
Reactant
Product
Elements Symbol
No. of atoms
Elements Symbol
No. of atoms
K
1
K
1
H
2
H
3
O
1
O
1
Now in order to balance the equation the number of atoms on both reactants and the products side should be equal. By applying hit and trialmethod the balanced equation of the given reaction is:
2K(s)+2H2O(l)→2KOH(aq)+H2(g)
Answer: Option B. -> Beaker B
:
B
Copper is less reactive than zinc and iron, but is more reactive than silver. Hence, copper displaces silver from its salt solution.
Copper on reaction with silver sulphate forms copper sulphate and silver. The solution colour changes as copper sulphate is blue in colour. The reaction takes place as follows:
2AgSO4(aq)+Cu(s)→2Ag(s)+CuSO4(aq)
Hence colour change will be observed in the case of beaker B.
:
B
Copper is less reactive than zinc and iron, but is more reactive than silver. Hence, copper displaces silver from its salt solution.
Copper on reaction with silver sulphate forms copper sulphate and silver. The solution colour changes as copper sulphate is blue in colour. The reaction takes place as follows:
2AgSO4(aq)+Cu(s)→2Ag(s)+CuSO4(aq)
Hence colour change will be observed in the case of beaker B.
Answer: Option A. -> decomposition
:
A
The conversion of calcium carbonate(CaCO)3 to calcium oxide(CaO) is an example of decomposition reaction. During the reaction, calcium carbonate decomposes on heating to form calcium oxide and carbon dioxide. The reaction takes place as follows:
CaCO3(s)Heat⟶CaO (s)+CO2(g)
:
A
The conversion of calcium carbonate(CaCO)3 to calcium oxide(CaO) is an example of decomposition reaction. During the reaction, calcium carbonate decomposes on heating to form calcium oxide and carbon dioxide. The reaction takes place as follows:
CaCO3(s)Heat⟶CaO (s)+CO2(g)
Answer: Option C. -> 2Na(s)+2H2O(l)→2NaOH(aq)+H2(g)
:
C
The chemical reaction in which a more reactive element displaces a less reactive element from its compound is called displacement reaction.
Among the given options, the reaction between sodium and water to form sodium hydroxide and hydrogen gas is an example of a displacement reaction. This is because sodium, which is more reactive than hydrogen, displaces it from water.
:
C
The chemical reaction in which a more reactive element displaces a less reactive element from its compound is called displacement reaction.
Among the given options, the reaction between sodium and water to form sodium hydroxide and hydrogen gas is an example of a displacement reaction. This is because sodium, which is more reactive than hydrogen, displaces it from water.
Answer: Option D. -> Small bubbles are formed
:
D
When zinc granules areadded todilute hydrochloric acid taken in a test tube, the zinc metal displaces the hydrogen from the acid and hydrogen gas comes out in the form of small bubbles. This is a displacement reaction. It occurs as follows:
Zn(s)+2HCl(aq)→ZnCl2(aq)+H2(g)ZincHydrochloricZincHydrogenacidchloride
:
D
When zinc granules areadded todilute hydrochloric acid taken in a test tube, the zinc metal displaces the hydrogen from the acid and hydrogen gas comes out in the form of small bubbles. This is a displacement reaction. It occurs as follows:
Zn(s)+2HCl(aq)→ZnCl2(aq)+H2(g)ZincHydrochloricZincHydrogenacidchloride
Answer: Option D. -> rancidity
:
D
When food containing fats and oils come in contact with oxygen in the air, it undergoes oxidation. This causes bad smell and change in taste of food. This process is called rancidity.
:
D
When food containing fats and oils come in contact with oxygen in the air, it undergoes oxidation. This causes bad smell and change in taste of food. This process is called rancidity.
Answer: Option C. -> decomposition reaction
:
C
A decomposition reaction is where one reactant is broken into multiple simple products.
When lead nitrate (2Pb(NO3)2) is heated, it decomposes into lead oxide (PbO), nitrogen dioxide (NO2) and oxygen (O2). The reaction occurs as follows:
2Pb(NO3)2(s)Heat⟶2PbO (s)+4NO2(g)+O2(g)
Thereddish brown gas released is NO2.
:
C
A decomposition reaction is where one reactant is broken into multiple simple products.
When lead nitrate (2Pb(NO3)2) is heated, it decomposes into lead oxide (PbO), nitrogen dioxide (NO2) and oxygen (O2). The reaction occurs as follows:
2Pb(NO3)2(s)Heat⟶2PbO (s)+4NO2(g)+O2(g)
Thereddish brown gas released is NO2.
Answer: Option C. -> white precipitate of CaCO3 is formed.
:
C
When CO2 is passed through lime water, a white precipitate of CaCO3 is formed, which turns lime water milky. The reaction occurs as follows:
Ca(OH)2(aq)+CO2(g)→CaCO3(s)↓+H2O(l)
:
C
When CO2 is passed through lime water, a white precipitate of CaCO3 is formed, which turns lime water milky. The reaction occurs as follows:
Ca(OH)2(aq)+CO2(g)→CaCO3(s)↓+H2O(l)
Answer: Option C. -> Ca(OH)2
:
C
Slaked lime (Ca(OH)2)is formed when quicklime (CaO)reacts with water. The equation of the reaction is given below:
CaO(s)+H2O(l)→Ca(OH)2(aq)+Heat
This is an example of a combination reaction because there is only one product that is being formed from the reaction between the tworeactants.
:
C
Slaked lime (Ca(OH)2)is formed when quicklime (CaO)reacts with water. The equation of the reaction is given below:
CaO(s)+H2O(l)→Ca(OH)2(aq)+Heat
This is an example of a combination reaction because there is only one product that is being formed from the reaction between the tworeactants.
Answer: Option A. -> MnO2
:
A
An oxidising agent is a chemical compound that undegoes reduction in a redox reaction. In the given reaction, manganese dioxide is behaving as an oxidising agent as it is getting reduced to manganese.
:
A
An oxidising agent is a chemical compound that undegoes reduction in a redox reaction. In the given reaction, manganese dioxide is behaving as an oxidising agent as it is getting reduced to manganese.