Question

A reddish brown coloured metal used in electric wires, when powdered and heated strongly in an open China dish, its colour rums black. When hydrogen gas is passed over this black substance, it regains its original colour. Based on this information, the metal and black coloured substances are
A. copper and copper nitrate
B. silver and silver oxide
C. copper and copper oxide
D. aluminium and aluminium oxide

Answer 1

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A reddish brown coloured metal used in electric wires, when powdered and heated strongly in an open China dish, its colour turns black. When hydrogen gas is passed over this black substance, it regains its original colour. Based on this information, the metal and black coloured substances are

A. copper and copper nitrate

B. silver and silver oxide

C. copper and copper oxide

D. aluminium and aluminium oxide

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C. copper and copper oxide

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$\sf{Reddish\:Brown\:coloured\:metal \longrightarrow Copper\:( Cu )}$

It is used in electric wires.

When it is heated strongly in air, the chemical equation will be:

$\tt{Cu + \dfrac{1}{2}O_2 \longrightarrow (\Delta) CuO\:(black\:coloured)}$

When it is passed through hydrogen gas, it regains its colour, the the chemical equation will be:

$\tt{CuO + H_2 \longrightarrow Cu + H_2O\:(brown\:coloured)}$

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So, the metal is copper (Cu) and the black coloured substance is copper oxide (CuO).

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Answer 2

AnSwEr:-

C. copper. and copper oxide.

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SteP By SteP ExplainaTion:-

★ When the metal copper heated strongly in an open china dish its color rums black which is copper oxide.

$\sf{2Cu+O_{2}\longrightarrow\:2CuO(black\:color)}$

★ When hydrogen gas passes through this Copper oxide. It turns into copper and water.

$\sf{CuO+H_{2}\longrightarrow\:Cu+H_{2}O(brown\:color)}$

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