RRB Group D 27 Nov 2025 Shift 3 Solved Paper

Concept:Acidity is measured by $\mathrm{pH}$; lower $\mathrm{pH}$ means higher acidity.Explanation:Lemon juice has the lowest $\mathrm{pH}$ (around $2$ to $3$) due to $\mathrm{citric\ acid}$, making it the most acidic among the options.Vinegar has $\mathrm{pH}$ $2.4$–$3.4$ (from $\mathrm{acetic\ acid}$), which is slightly less acidic than lemon juice.Milk is slightly acidic with $\mathrm{pH}$ approximately $6.5$ to $6.7$.Water is neutral with $\mathrm{pH}$ $7$, showing no acidity.Therefore, lemon juice has the highest acidity.Answer:C. Lemon juice