How To Unblock A Drain With Baking Soda ((link)) -

Immediately pour 1 cup of white vinegar into the drain. A vigorous fizzing reaction will begin.

Cover the drain opening with a rubber stopper or a damp cloth to contain the CO₂ pressure, forcing it down into the clog. Leave for 15–30 minutes. how to unblock a drain with baking soda

Pour ½ cup of baking soda directly into the drain. Use a funnel if needed to ensure it reaches the pipe. Immediately pour 1 cup of white vinegar into the drain