Question

Observe the given figure carefully and identify the substances marked as (p), (q) and (r).

A. (p) - zinc, (q) - water, (r) - carbon dioxide
B. (p) -Magnesium, (q) -hydrochloric acid, (r) - oxygen
C. p) -Magnesium, (q) - water, (r) - carbon dioxide
D. p) - zinc, (q) - Hydrochloric acid, (r) - Hydrogen

Answer 1

Hint: The first element of periodic when brought near to the burning splinter makes the popping sound. When the gas reacts with oxygen then only it will make a pop sound. Whereas those gases who cannot react with oxygen will make a pop sound.

Complete step by step answer:
- In the given question we have to identify the three molecules or atoms that are p, q and r.
- Now, as we know that the gas which is released after the completion of reaction makes the pop sound.
- So, the gas must be hydrogen because when a burning splinter is brought near to the hydrogen gas it reacts with oxygen and makes a pop sound.
- So, according to it (r) will be hydrogen due to which option D will be the correct answer in the given question.
- Now, to prove it, we see the reaction between zinc and hydrochloric acid because according to the diagram (p) and (q) are dissolved with each other to react. So, the balanced reaction will be:
\[\text{Zn + 2HCl }\to \text{ ZnC}{{\text{l}}_{2}}\text{ + }{{\text{H}}_{2}}\]

- So, as we can see that zinc and hydrochloric acid react to the released hydrogen gas which makes the pop sound. So, the correct answer is “Option D”.

Note: The gases like carbon dioxide, oxygen don't produce a pop sound when a burning splinter is brought near to them. When magnesium reacts with water it yields hydrogen gas and not carbon dioxide. Also, when magnesium reacts with $\text{HCl}$ it yields ${{\text{H}}_{2}}$ and not ${{\text{O}}_{2}}$ and when zinc reacts with ${{\text{H}}_{2}}\text{O}$ it yields $\text{Zn(OH}{{\text{)}}_{2}}$ & ${{\text{H}}_{2}}$ and not $\text{C}{{\text{O}}_{2}}$.