A student takes $Na_2CO_3$ powder in a test tube and pours some drops of acetic acid over it. He observes :

When acetic acid ($CH_3COOH$) reacts with sodium carbonate ($Na_2CO_3$), a chemical reaction occurs producing sodium acetate, water, and carbon dioxide ($CO_2$) gas. The chemical equation is:

$$2CH_3COOH + Na_2CO_3 \rightarrow 2CH_3COONa + H_2O + CO_2 \uparrow$$

The carbon dioxide gas is released with brisk effervescence, which is observed as bubbles of a colourless and odourless gas. Therefore, option C is correct.

• Option A is incorrect because a vigorous chemical reaction occurs.
• Option B is incorrect because $CO_2$ is odourless, not pungent.
• Option D is incorrect because no white fumes are formed; the gas evolved is carbon dioxide which is invisible.