When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it?

Chemical change

The correct answer is option 2. Chemical change.

When baking soda is mixed with lemon juice, and bubbles are formed with the evolution of a gas, it is indicative of a chemical change. Therefore, the correct answer is Chemical change

1. Chemical Change:

In this reaction, baking soda (sodium hydrogen carbonate, NaHCO₃) reacts with lemon juice (citric acid) to produce carbon dioxide gas (CO₂), water (H₂O), and a soluble salt (sodium citrate):

\[ \text{NaHCO}_3 + \text{H}^+(\text{from lemon juice}) \rightarrow \text{CO}_2 + \text{H}_2\text{O} + \text{Na}^+(\text{from sodium citrate}) \]

2. Gas Evolution:

The formation of bubbles and the evolution of a gas (carbon dioxide) are characteristic signs of a chemical change. The reaction involves the breaking and forming of chemical bonds, resulting in the conversion of reactants into new substances.

3. Physical Change vs. Chemical Change:

In a physical change, the substance undergoes a change in its physical state or appearance without a change in its chemical composition. In a chemical change, the substance undergoes a transformation at the molecular level, resulting in the formation of new substances with different chemical properties.

In the case of baking soda and lemon juice, the reaction involves a chemical change as new substances are formed (carbon dioxide, water, and salt), and this is accompanied by the release of gas in the form of bubbles.