Question

A black substance which on treatment with HCL liberates greenish yellow gas

Answer 1

Because, the evolved gas is pungent and greenish yellow in colour, this confirms that the gas is chlorine gas .

Now,

When this salt reacts with concentrated Hydrochloric acid, and that the salt is also black in colour, so it definitely has to be Manganese Dioxide. (MnO2)

So final reaction becomes :-

MnO2 + HCl gives MnCl2 + HCl

Hope it helps.

Answer 2

Here's your answer mate....

The gas liberated in this reaction is greenish yellow so obviously it would be chlorine gas...

And the black substance in this reaction is MnO2....

If you need more help then refer the attached picture......

Hope it helped you.....

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