Question

which of the following reaction does not give hydrogen gas?
a)Zn+dilNaOH
b)NaH+H2O
c)Na=liq.NH3
d)Cu+dil.H2SO4

Answer 1

c is the right answer.
By the reaction of sodium with liquid ammonia sodium amide is be prepared hydrogen is not released.

Answer 2

Answer:

The reaction that doesn't give Hydrogen gas is Na + liq. NH₃ and Cu + dil. H2SO4.

Explanation:

1. $Zn + 2NaOH \rightarrow H_2 + Na_2ZnO_2$

Zinc, upon exposure to dilute NaOH in excess, forms sodium zincate, and releases Hydrogen gas. This metal, being one of transition, exhibits medium reactivity.

2. $NaH+H_2O \rightarrow NaOH+H_2$

This reaction is a type of displacement reaction, with redox taking place. Here, hydrogen gas is evolved by reducing water.

3. $Na + NH_3 _(_l_) \rightarrow [Na(NH_3)_x]^+ + [e(NH_3)_y]^-$

Sodium, when reacting with liquid ammonia, it forms ammoniated ions and electrons, with NO evolution of hydrogen gas. This solution is paramagnetic, too.

4. $Cu + H_2SO_4 _(_a_q_) \rightarrow no\; reaction$

In the reactivity series, Copper is much less reactive than hydrogen, and thus, doesn't displace hydrogen from sulphuric acid, thereby not evolving Hydrogen gas, either.

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