The pH of a solution that turns red litmus blue is most likely: MCQ with Answer and Explanation

Explanation:
Biogas is produced by anaerobic decomposition of organic matter (cow dung, agricultural waste) and typically contains 50-70% methane (CH₄), 30-40% CO₂, and traces of H₂S, NH₃, and H₂. Methane provides the fuel value. Biogas is a renewable fuel used for cooking and electricity generation. The slurry is good manure.

Explanation:
Urea (NH₂CONH₂) contains about 46% N. Ammonium sulfate ~21% N, sodium nitrate ~16% N, DAP ~18% N (and 46% P₂O₅). Urea is the most concentrated solid nitrogen fertilizer.

Explanation:
Ozone (O₃) is a powerful disinfectant that decomposes to O₂, leaving no residual taste or odor. However, it must be generated on-site and provides no lasting protection. Chlorine leaves residual.