Chemical Reactions and Equations - Case Based Questions

Q 1 :
Read the passage carefully and answer the following questions from (i) to (v):

Equations must always be balanced. The numbers of atoms of each type involved in a chemical reaction are the same on the reactant and product sides of the equation.
In a combination reaction, two or more substances combine to form a new single substance. In a decomposition reaction, a single substance decomposes to give two or more substances. When an element displaces another element from its compound, a displacement reaction occurs. Reactions also involve gain or loss of oxygen or hydrogen by substances. Oxidation = gain of oxygen or loss of hydrogen. Reduction = loss of oxygen or gain of hydrogen.

Which of the following reactions is not correct?

$Z n + C u S O_{4} \to Z n S O_{4} + C u$
$2 A g + C u {(N O_{3})}_{2} \to 2 A g N O_{3} + C u$
$F e + C u S O_{4} \to F e S O_{4} + C u$
$M g + 2 H C l \to M g C l_{2} + H_{2}$

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(2)

Q 2 :
Read the passage carefully and answer the following questions from (i) to (v):

Equations must always be balanced. The numbers of atoms of each type involved in a chemical reaction are the same on the reactant and product sides of the equation.
In a combination reaction, two or more substances combine to form a new single substance. In a decomposition reaction, a single substance decomposes to give two or more substances. When an element displaces another element from its compound, a displacement reaction occurs. Reactions also involve gain or loss of oxygen or hydrogen by substances. Oxidation = gain of oxygen or loss of hydrogen. Reduction = loss of oxygen or gain of hydrogen.

Which of the following is not a displacement reaction?

Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water
Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride
Aluminium + Copper chloride → Aluminium chloride + Copper
(d) Potassium bromide(aq) + Barium iodide(aq) → Potassium iodide(aq) + Barium bromide(s)

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(1)

Q 3 :
Read the passage carefully and answer the following questions from (i) to (v):

Equations must always be balanced. The numbers of atoms of each type involved in a chemical reaction are the same on the reactant and product sides of the equation.
In a combination reaction, two or more substances combine to form a new single substance. In a decomposition reaction, a single substance decomposes to give two or more substances. When an element displaces another element from its compound, a displacement reaction occurs. Reactions also involve gain or loss of oxygen or hydrogen by substances. Oxidation = gain of oxygen or loss of hydrogen. Reduction = loss of oxygen or gain of hydrogen.

Identify the correct chemical reaction.

Hydrogen sulphide gas burns in air to give water and sulphur.
Potassium metal reacts with water to give potassium hydroxide and water.
Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
Zinc reacts with silver nitrate to form zinc nitrite and silver.

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(3)

Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.

Q 4 :
Read the passage carefully and answer the following questions from (i) to (v):

Equations must always be balanced. The numbers of atoms of each type involved in a chemical reaction are the same on the reactant and product sides of the equation.
In a combination reaction, two or more substances combine to form a new single substance. In a decomposition reaction, a single substance decomposes to give two or more substances. When an element displaces another element from its compound, a displacement reaction occurs. Reactions also involve gain or loss of oxygen or hydrogen by substances. Oxidation = gain of oxygen or loss of hydrogen. Reduction = loss of oxygen or gain of hydrogen.

Which of the following reactions will evolve hydrogen gas with a pop sound?

Concentrated nitric acid is reacted with sulphur.
A small piece of zinc is added to dilute hydrochloric acid.
Ammonia is passed over heated copper (II) oxide.
Lead nitrate is heated strongly in a test tube.

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A small piece of zinc is added to dilute hydrochloric acid.

Q 5 :
Read the passage carefully and answer the following questions from (i) to (v):

Equations must always be balanced. The numbers of atoms of each type involved in a chemical reaction are the same on the reactant and product sides of the equation.
In a combination reaction, two or more substances combine to form a new single substance. In a decomposition reaction, a single substance decomposes to give two or more substances. When an element displaces another element from its compound, a displacement reaction occurs. Reactions also involve gain or loss of oxygen or hydrogen by substances. Oxidation = gain of oxygen or loss of hydrogen. Reduction = loss of oxygen or gain of hydrogen.

Identify the type of reaction in the following:

$F e + C u S O_{4} (a q) ⟶ F e S O_{4} (a q) + C u (s)$

Oxidation Reaction
Redox Reaction
Combustion Reaction
None of these

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Redox Reaction

Q 6 :
Read the passage carefully and answer the following questions from (i) to (v):

Balanced chemical equation has an equal number of atoms of different elements in the reactants and products. According to law of conservation of mass, matter can neither be created nor be destroyed in a chemical reaction.

Which of the following equation are balanced?

$3 F e (s) + 4 H_{2} O (g) \to F e_{3} O_{4} (s) + 4 H_{2} (g)$
$2 C a O (s) + H_{2} O (l) \to 2 C a {(O H)}_{2} (a q)$
$C H_{4} (g) + 2 O_{2} (g) \to C O_{2} (g) + 2 H_{2} O (g)$
$2 A g B r (s) \to A g (s) + 2 B r_{2} (g)$

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(1)

Q 7 :
Read the passage carefully and answer the following questions from (i) to (v):

Balanced chemical equation has an equal number of atoms of different elements in the reactants and products. According to law of conservation of mass, matter can neither be created nor be destroyed in a chemical reaction.

The following represent the exothermic reaction. The reactants react to form product, with the release of energy in the form of heat

Which of the following involve an exothermic reaction?

Respiration
Oxidation
Combustion
All of these

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(4)

Q 8 :
Read the passage carefully and answer the following questions from (i) to (v):

Balanced chemical equation has an equal number of atoms of different elements in the reactants and products. According to law of conservation of mass, matter can neither be created nor be destroyed in a chemical reaction.

When the powder of a common metal is heated in an open china dish, its colour turns black. However, when hydrogen is passed over the hot black substance so formed, it regains its original colour. What type of chemical reaction takes place in each of the two given steps?

First oxidation reaction then displacement reaction
First combustion reaction, then reduction reaction
First oxidation reaction, then redox reaction
First reduction reaction, then redox reaction

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First oxidation reaction, then redox reaction

Q 9 :
Read the passage carefully and answer the following questions from (i) to (v):

Balanced chemical equation has an equal number of atoms of different elements in the reactants and products. According to law of conservation of mass, matter can neither be created nor be destroyed in a chemical reaction.

Study the given diagram in which white powder of silver chloride was left open in sunlight. After few hours, it was observed that the white powder changed to silvery material. What type of reaction is it?

Displacement reaction
Decomposition reaction
Decomposition reaction
Corrosion

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Decomposition reaction

Q 10 :
Read the passage carefully and answer the following questions from (i) to (v):

Balanced chemical equation has an equal number of atoms of different elements in the reactants and products. According to law of conservation of mass, matter can neither be created nor be destroyed in a chemical reaction.

After rain, Shreya observed that an iron lock developed a reddish-brown powdery covering after rain. She cleaned it with sandpaper and found a shiny layer beneath. What could she do to prevent such corrosion from occurring again?

To buy a new similar lock
To coat the surface with a layer of paint
To clean the lock using sandpaper regularly
To buy a gold lock instead of an iron lock

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To coat the surface with a layer of paint

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