Nascent hydrogen is prepared by

(A) $\ce{Na}$ and $\ce{C2H5OH}$
(B) $\ce{Al}$ and $\ce{NaOH}$
(C) $\ce{Zn}$ and dil. $\ce{H2SO4}$
(D) All of these

My attempt

I know that option (A) & option (C) are correct option. But don't know about option (C) and in the answer all of them are correct.

Can someone provide the complete reaction about option (B) and its important information such as similar reactions or mechanism?

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    $\begingroup$ Why downvote? I don't understand?! $\endgroup$
    – jayant98
    Aug 25, 2018 at 15:22
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    – A.K.
    Aug 25, 2018 at 18:05

1 Answer 1


Zinc and sulfuric acid react to form nascent hydrogen. From chem-guide.blogspot.com (emphasis mine):

[…] if ordinary hydrogen is passed through acidified $\ce{KMnO4}$ it does not get decolourised. However, if zinc pieces are added to the same solution, bubbles of hydrogen rise up through the solution and the colour is discharged due to the reduction of $\ce{KMnO4}$ by nascent hydrogen.

$$ \begin{align} \ce{KMnO4 + \underset{molecular}{H2} + H2SO4 &-> \text{No reaction}} \\ \ce{Zn + H2SO4 &-> ZnSO4 + \underset{nascent hydrogen}{2H}} |\times 5 \\ \ce{2 kMnO4 + H2SO4 + 10 [H] &-> K2SO4 + 2 MnSO4 + 8 H2O} \\ \hline \ce{5 Zn + 8 H2SO4 + 2 KMnO4 &-> 5 ZnSO4(aq) + K2SO4 + 2 MnSO4 + 8 H2O} \end{align} $$

See this youtube video for more information.

As for the reaction given in option (B), see previous SE questions: this, this and this.


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