Question

When dilute hydrochloric acid is added to zinc pieces taken in a test tube:

• A. No change takes place.
• B. Small bubbles of a gas appear on the surface of zinc pieces.
• C. The colour of the solution turns yellow.
• D. The gas released will give a pop sound with a glowing splinter.

Answer 1

Answer: (B), (D)

The correct options are
B Small bubbles of a gas appear on the surface of zinc pieces.
D The gas released will give a pop sound with a glowing splinter.

When dilute hydrochloric acid is added to zinc pieces taken in a test tube, the zinc metal displaces the hydrogen from the acid and hydrogen gas comes out in the form of small bubbles. Hydrogen gas gives a pop sound with glowing splinter. This is a displacement reaction. It occurs as follows:

$\text{Zn}+2\text{HCl}\text{(dil.)}\to {\text{ZnCl}}_2+\underset{\text{Hydrogen gas}}{{\text{H}}_2}\uparrow$