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Hydrogen

Short Answer Type

151.

Complete the following chemical reactions.
PbS + H₂O₂ (aq) $rightwards arrow$

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152.

Complete the following chemical reactions.
$MnO subscript 4 superscript minus left parenthesis aq right parenthesis space plus space straight H subscript 2 straight O subscript 2 left parenthesis aq right parenthesis space rightwards arrow$

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153.

How does hydrogen peroxide act as bleaching agent?

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154.

Give two chemical reactions which show the acidic character of hydrogen peroxide.

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155. Hydrogen peroxide is used to restore the colour of old oil paintings containing lead oxide. Write a balanced equation for the reaction that takes place in this process.

When an oil painting is constantly exposed to the atmosphere, the traces of hydrogen sulphide gas present in the atmosphere slowly blackens the painting by converting lead oxide (white) to lead sulphide (black).

Now, when the painting is dipped in a dilute solution of H₂O₂ for some time, lead sulphide is slowly oxidised to white lead sulphate.

Thus the colour of lead painting is restored.