When dilute hydrochloric acid is added to granulated zinc placed in a test tube, the observation made is:
A) The surface of metal turns shining.
B) The reaction mixture turns milky.
C) The odour of chlorine is observed.
D) A colourless and odourless gas evolves with bubbles.

Hint: We know that zinc is a metal. Metals participate in oxidation and reduction reactions when they are treated with appropriate reagents. To solve this we must know what happens when zinc reacts with hydrochloric acid

Complete step by step answer:
We know that the atomic number of zinc is 30. The electronic configuration of zinc is $1{s^2}2{s^2}2{p^6}3{s^2}3{d^{10}}4{s^2}$.
The outermost shell of zinc i.e. 4s shell contains two valence electrons. Zinc has a tendency to lose the two electrons and gain a +2 oxidation state. Thus, zinc undergoes oxidation by losing electrons and forms ${\text{Z}}{{\text{n}}^{2 + }}$ ion.
We know that hydrochloric acid $\left( {{\text{HCl}}} \right)$ is a strong acid. Hydrochloric acid donates a proton and accepts an electron from the metal.
When dilute hydrochloric acid is added to granulated zinc placed in a test tube, zinc metal is converted to zinc chloride and hydrogen gas is evolved in the reaction.