NCERT Exemplar XXIV — task. Science CBSE, Class 9.

PDF chapter test TRY NOW

Write brief answers to the following question:

Iron filings and sulphur were mixed together and divided into two parts, ‘A’ and ‘B’. Part ‘A’ was heated strongly while Part ‘B’ was not heated. Dilute hydrochloric acid was added to both the Parts and evolution of gas was seen in both the cases. How will you identify the gases evolved?

Part A:

Fe(s) + S(s) →

FeS + 2HCl(aq) → +

$H_2S$

Part B:

+ S(s) → Mixture of iron filings and sulphur

When dilute HCl is added to it

Fe(s) + S(s) + 2HCl(aq) → +

$H_2$ gas

Sulphur remains unreacted

$H_2S$ gas formed has a foul smell and on passing through lead acetate solution, it turns the solution . Hydrogen gas burns with a pop sound.