Which of the following makes bread soft and spongy when baking soda is added?

Baking soda, or sodium hydrogencarbonate (NaHCO3), acts as a leavening agent in baking. When it is heated or reacts with a mild edible acid (like tartaric acid in baking powder), a chemical reaction occurs that releases carbon dioxide (CO2) gas [2]. This CO2 gas forms bubbles within the dough or batter, causing it to rise and expand [4]. The trapped gas bubbles create a light, porous structure, which is what makes the final bread or cake soft and spongy [1]. While NaHCO3 is the reactant and water or sodium salts may be products of the reaction, it is specifically the production and expansion of CO2 gas that provides the physical leavening effect required for the spongy texture [3].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Uses of Baking soda > p. 31
2. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > Activity 5.4: Let us experiment > p. 61
3. [4] https://pmc.ncbi.nlm.nih.gov/articles/PMC8056436/
4. [3] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Activity 4.9 > p. 74