Chemistry: Chemical Reaction And Equation Questions!

1. Which one is a double displacement reaction?

BaCl2 + Na2SO4 --------> BaSO4 + 2NaCl

CaO + H2O ------------> Ca(OH)2

2Pb(NO3)2 --------> 2PbO + 4NO2 + O2

Zn + 2AgNO3 ----------> Zn(NO3)2 + 2Ag

The reaction BaCl2 + Na2SO4 -> BaSO4 + 2NaCl is a double displacement reaction because the cations and anions in the reactants exchange places to form new compounds. Ba2+ from BaCl2 combines with SO42- from Na2SO4 to form BaSO4, and Na+ from Na2SO4 combines with Cl- from BaCl2 to form NaCl. This type of reaction is also known as a precipitation reaction because one of the products, BaSO4, is insoluble and forms a precipitate.

Explanation

The reaction BaCl2 + Na2SO4 -> BaSO4 + 2NaCl is a double displacement reaction because the cations and anions in the reactants exchange places to form new compounds. Ba2+ from BaCl2 combines with SO42- from Na2SO4 to form BaSO4, and Na+ from Na2SO4 combines with Cl- from BaCl2 to form NaCl. This type of reaction is also known as a precipitation reaction because one of the products, BaSO4, is insoluble and forms a precipitate.

2. Zinc + Sulphuric acid → Zinc sulphate + (X) What will be the product "X"?

Hydrogen

ZnO

Zinc Sulphite

Nitrogen

When zinc reacts with sulphuric acid, it displaces hydrogen from the acid to form zinc sulphate and hydrogen gas. Therefore, the product "X" in this reaction will be hydrogen.

Explanation

When zinc reacts with sulphuric acid, it displaces hydrogen from the acid to form zinc sulphate and hydrogen gas. Therefore, the product "X" in this reaction will be hydrogen.

3. CaO- calcium Oxide reaction with water is regarded as exothermic. A student mixes these two products in a test tube and touches its side surface. Which of the following statement correctly describes the student's observation?

The test tube becomes cold due to release of heat energy

The test tube becomes hot due to release of heat energy

The test tube becomes hot due to absorption of heat energy

The test tube becomes cold due to absorption of heat energy

When calcium oxide (CaO) reacts with water, it undergoes an exothermic reaction, meaning that heat energy is released. When the student mixes these two products in a test tube and touches its side surface, they would observe that the test tube becomes hot. This is because the heat energy released during the exothermic reaction is transferred to the test tube, causing it to increase in temperature.

Explanation

When calcium oxide (CaO) reacts with water, it undergoes an exothermic reaction, meaning that heat energy is released. When the student mixes these two products in a test tube and touches its side surface, they would observe that the test tube becomes hot. This is because the heat energy released during the exothermic reaction is transferred to the test tube, causing it to increase in temperature.

4. Aluminum reacts with copper sulphate to produce

Cu and Al2(SO4)3

CuO and Al2(SO4)3

Cu, Al2S3 and SO2

CuO, Al2S3 and SO2

When aluminum reacts with copper sulphate, the copper ions in the copper sulphate solution are reduced to copper metal, while the aluminum is oxidized to form aluminum sulfate (Al2(SO4)3). Therefore, the products of the reaction are Cu and Al2(SO4)3.

Explanation

When aluminum reacts with copper sulphate, the copper ions in the copper sulphate solution are reduced to copper metal, while the aluminum is oxidized to form aluminum sulfate (Al2(SO4)3). Therefore, the products of the reaction are Cu and Al2(SO4)3.

5. What happens when dilute HCl is added to iron filings? Tick the correct answer.

Hydrogen gas and iron chloride are produced.

Chlorine gas and iron hydroxide are produced.

No reaction takes place.

Iron salt and water are produced.

When dilute HCl is added to iron filings, a chemical reaction occurs. The HCl (hydrochloric acid) reacts with the iron (Fe) to form iron chloride (FeCl2) and hydrogen gas (H2). This is a typical example of a metal-acid reaction, where the metal displaces the hydrogen in the acid, resulting in the formation of a salt (iron chloride) and the evolution of hydrogen gas.

Explanation

When dilute HCl is added to iron filings, a chemical reaction occurs. The HCl (hydrochloric acid) reacts with the iron (Fe) to form iron chloride (FeCl2) and hydrogen gas (H2). This is a typical example of a metal-acid reaction, where the metal displaces the hydrogen in the acid, resulting in the formation of a salt (iron chloride) and the evolution of hydrogen gas.

6. Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium choloride. Which of the following correctly represents the type of the reaction involve? i. Displacement reaction ii. Precipitation reaction iii. Combination reaction iv. Double displacement reaction

(i) , (iii)

(ii), (iii)

(iii)

(ii), (iv)

The given reaction involves the formation of a solid precipitate (barium sulphate) and the exchange of ions between the reactants (barium chloride and ammonium sulphate). This type of reaction is known as a precipitation reaction. Additionally, since the ions from both reactants switch partners to form new compounds, it can also be classified as a double displacement reaction. Therefore, the correct answer is (ii), (iv).

Explanation

The given reaction involves the formation of a solid precipitate (barium sulphate) and the exchange of ions between the reactants (barium chloride and ammonium sulphate). This type of reaction is known as a precipitation reaction. Additionally, since the ions from both reactants switch partners to form new compounds, it can also be classified as a double displacement reaction. Therefore, the correct answer is (ii), (iv).

7. Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form its solution called lime water. Which among the following is (are) true about slaking of lime and the solution formed ? i. It is an endothermic reaction ii. It is an exothermic reaction iii. The pH of the resulting solution will be more than seven iv. The pH of the resulting solution will be less than seven

(i) and (ii)

(ii) and (iii)

(i) and (iv)

(iii) and (iv)

The slaking of lime, which is the reaction between solid calcium oxide and water, is an exothermic reaction because heat is liberated during the process. This means that it releases energy in the form of heat. Additionally, the resulting solution, calcium hydroxide or lime water, will have a pH higher than seven. This indicates that it is alkaline or basic in nature. Therefore, the correct answer is (ii) and (iii).

Explanation

The slaking of lime, which is the reaction between solid calcium oxide and water, is an exothermic reaction because heat is liberated during the process. This means that it releases energy in the form of heat. Additionally, the resulting solution, calcium hydroxide or lime water, will have a pH higher than seven. This indicates that it is alkaline or basic in nature. Therefore, the correct answer is (ii) and (iii).

8. Which of the following is not a balanced equation?

H2 + O2 H2O

Mg + CuSO2 MgSO4 + Cu

NaOH + HCl NaCI + H2O

Zn + S ZnS

not-available-via-ai

Explanation

not-available-via-ai

9. Which of the following are exothermic processes-

Reaction of water with quick lime
Dilution of an acid
Evaporation of water
Sublimation of camphor crystals

(i) and (ii)

(ii) and (iii)

(i) and (iv)

(iii) and (iv)

The reaction of water with quick lime is exothermic because it releases heat energy. This is because the reaction between water and quick lime is highly exothermic and produces calcium hydroxide as a product. Dilution of an acid is also exothermic because it releases heat energy. When an acid is diluted with water, it releases heat due to the exothermic nature of the reaction. Therefore, both (i) and (ii) are exothermic processes.

Explanation

The reaction of water with quick lime is exothermic because it releases heat energy. This is because the reaction between water and quick lime is highly exothermic and produces calcium hydroxide as a product. Dilution of an acid is also exothermic because it releases heat energy. When an acid is diluted with water, it releases heat due to the exothermic nature of the reaction. Therefore, both (i) and (ii) are exothermic processes.

10. The electrolytic decomposition of water gives H₂ and O₂in the ration of

1:2 by volume

2:1 by volume

8:1 by mass

1:2 by mass

The electrolytic decomposition of water produces hydrogen and oxygen gases. According to Avogadro's law, equal volumes of gases at the same temperature and pressure contain an equal number of molecules. Since the molecular formula of water is H2O, it means that for every molecule of water decomposed, two molecules of hydrogen gas (H2) and one molecule of oxygen gas (O2) are produced. Therefore, the ratio of hydrogen to oxygen gases produced by volume is 2:1.

Explanation

The electrolytic decomposition of water produces hydrogen and oxygen gases. According to Avogadro's law, equal volumes of gases at the same temperature and pressure contain an equal number of molecules. Since the molecular formula of water is H2O, it means that for every molecule of water decomposed, two molecules of hydrogen gas (H2) and one molecule of oxygen gas (O2) are produced. Therefore, the ratio of hydrogen to oxygen gases produced by volume is 2:1.

11. Which among the following are endothermic processes? i. Reaction of quick lime with water ii. Dilution acid with water iii. Evaporation of water iv. Sublimation of solid ammonium chloride

(i) and (ii)

(ii) and (iii)

(i) and (iv)

(iii) and (iv)

not-available-via-ai

Explanation

not-available-via-ai

12. Which of the statements about the reaction below are incorrect? 2PbO(s) + C(s) → 2Pb(s) + CO2 (g) i. Lead is getting reduced. ii. Carbon dioxide is getting oxidized. iii. Carbon is getting oxidized. iv. Lead oxide is getting reduced.

(i) and (ii)

(i) and (iii)

(i), (ii) and (iii)

(iv) only

In the given reaction, lead oxide (PbO) is being reduced to lead (Pb) and carbon (C) is being oxidized to carbon dioxide (CO2). Therefore, statement (i) is correct as lead is indeed getting reduced. Similarly, statement (ii) is correct as carbon dioxide is indeed getting oxidized. Therefore, the correct answer is (i) and (ii).

Explanation

In the given reaction, lead oxide (PbO) is being reduced to lead (Pb) and carbon (C) is being oxidized to carbon dioxide (CO2). Therefore, statement (i) is correct as lead is indeed getting reduced. Similarly, statement (ii) is correct as carbon dioxide is indeed getting oxidized. Therefore, the correct answer is (i) and (ii).

13. What are the coefficients of the correctly balanced equations? ----Fe₂O₃+ ----CO

----Fe + ---CO₂

0,2,2,3

1,3,2,3

1,2,2,2

2,6,4,3

The coefficients of the correctly balanced equation are 1, 3, 2, and 3. This means that in order to balance the equation, we need 1 molecule of Fe2O3, 3 molecules of CO, 2 molecules of Fe, and 3 molecules of CO2.

Explanation

The coefficients of the correctly balanced equation are 1, 3, 2, and 3. This means that in order to balance the equation, we need 1 molecule of Fe2O3, 3 molecules of CO, 2 molecules of Fe, and 3 molecules of CO2.

14. A dilute ferrous sulpahte solution was gradually added to the beaker containing acidified KMnO₄ solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?

KMnO4 is oxidizing agent, it oxidizes FeSO4

FeSO4 acts as an oxidizing agent and oxidizes KMnO4

The color disappears due to dilution: no reaction is involved

KMnO4 is an unstable compound and decomposes in presence of FeSO4 to a colorless compound.

KMnO4 is a strong oxidizing agent and can oxidize FeSO4. The light purple color of KMnO4 solution is due to the presence of MnO4- ions, which are reduced to Mn2+ ions during the oxidation reaction. As FeSO4 is oxidized, it loses its ability to produce the light purple color, resulting in the fading and disappearance of the color of the solution.

Explanation

KMnO4 is a strong oxidizing agent and can oxidize FeSO4. The light purple color of KMnO4 solution is due to the presence of MnO4- ions, which are reduced to Mn2+ ions during the oxidation reaction. As FeSO4 is oxidized, it loses its ability to produce the light purple color, resulting in the fading and disappearance of the color of the solution.

15. Which of the following reactions is used in which washing of walls?

2Ca+O2 2CaO

Ca(OH)2 heat CaO+ H2O

Ca(OH)+CO2 CaCO3+H2O

CaO+H2O Ca(OH)2

This reaction is used in the washing of walls to remove carbon dioxide (CO2) from the air and form calcium carbonate (CaCO3) and water (H2O).

Explanation

This reaction is used in the washing of walls to remove carbon dioxide (CO2) from the air and form calcium carbonate (CaCO3) and water (H2O).