Question

1. When hydrogen is passed over black Solid Compound A.
the products are colourless liqued and a blank
. reddish brown substance B. The substance
B has two part and each part is placed in two
Separate test tube and to one part of the
substance Bodilute Hel is added, and to the
other part but dil. HNO₃ is added.
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Answer 1

The black colour solid compound A is CuO (cupric oxide)

When hydrogen gas is passed over it, the reaction undergoes as

$\sf CuO + H_2 \rightarrow Cu + H_2O$

Cupric oxide reacts with hydrogen to form copper and water.

Hence, the compound B is copper metal.

When Cu is added to dilute HCl, no reaction takes place as Cu is less reactive than hydrogen.

But, as Cu is added to dilute $\sf HNO_3$, it reacts and the reaction follows :

$\sf 3Cu + 8HNO_3 \rightarrow 3Cu(NO_3)_2 + 2NO+4H_2O$

$\sf HNO_3$ is a strong oxidising agent, thus it oxidises the hydrogen to water and itself gets reduced to any of the oxides of nitrogen.

Answer 2

Answer:

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