Question

Which one of the following setups is the most appropriate for the evolution of hydrogen gas and its identification?



(1) (a)
(2) (b)
(3) (c)
(4) (d)

Answer 1

When zinc reacted with dilute sodium hydroxide, hydrogen gas is evolved, which can be easily tested in the second test tube as there is proper space for the gas to be tested.
$\mathrm{Zn}\left(\mathrm{s}\right)+\mathrm{NaOH}\left(\mathrm{aq}\right)\to {\mathrm{Na}}_2{\mathrm{ZnO}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

Hence, the correct answer is option 2.