Question 7 - Case Based Questions (MCQ) - Chapter 1 Class 10 - Chemical Reactions and Equations

The following diagram displays a chemical  reaction. Observe carefully and answer any four questions from (a) to (e):

(a) The type of chemical reaction that will take place  is  

(i) Photochemical decomposition  

(ii) Displacement reaction  

(iii) Reduction reaction  

(iv) Combination reaction  

Ans. 

Let’s look at all the options one-by-one

• Photochemical decomposition : Photo means light, therefore the reactions in which a compound is broken down/decomposed in the presence of light are known as photochemical reactions.
• Displacement reaction : Reaction in which more reactive element takes the place of less reactive element.
• Reduction : The loss of oxygen is known as reduction. 
• Combination Reaction : When two or more substances react to form a single product, it is known as combination reaction.

Since the above reaction is taking place in the presence of light, it is a photochemical decomposition reaction.

So, the correct answer is (i) 

(b) What colour change is observed in silver  chloride?  

(i) Silver chloride turns white.  

(ii) Silver chloride turns brown.  

(iii) Silver chloride shows no colour change.  

(iv) White silver chloride changes to grey.  

Ans. 

Silver chloride (AgCl) is a white colored compound which decomposes to produce grey (Ag) colored silver.

So, the correct answer is (i).

(c) The correct balanced chemical equation involves:  

(i) 2AgCl (s) sunlight  ¾ →   ¾ ¾ 2Ag (s) + Cl ₂ (g)  

(ii) Ag + Cl → AgCl  

(iii) AgCl ₂ → Ag ₂ + Cl ₂   

(iv) AgCl sunlight  ¾ →   ¾ ¾ 2Ag + Cl ₂   

Ans. 

So, the correct answer is (i) 2AgCl (s) sunlight  ¾ →   ¾ ¾ 2Ag (s) + Cl ₂ (g)  

(d) When decomposition is carried out by heating, it is  called as:    

(i) Heat decomposition  

(ii) Photolytic decomposition  

(iii) Electrolytic decomposition  

(iv) Thermal decomposition  

Ans. 

So, the correct answer is (iv) Thermal decomposition

Explanation:

(e) The other silver salt which behaves like silver chloride in sunlight is:   

(i) silver hydride  

(ii) silver bromide  

(iii) silver iodide  

(iv) silver nitrite  

Ans. 

Silver Bromide behaves like Silver Chloride

So, the correct answer is (ii)