The reduction of a metal oxide by carbon at high temperature is known as: MCQ with Answer and Explanation

Explanation:
Nickel (finely divided) is used as a catalyst in the hydrogenation of unsaturated vegetable oils to saturated fats (vanaspati ghee). The reaction adds H₂ across double bonds. Platinum and palladium are also hydrogenation catalysts but nickel is cheaper and industrially preferred. Fe is used in Haber process for ammonia synthesis, V₂O₅ in contact process for H₂SO₄. Catalysts provide an alternative pathway with lower activation energy.

Explanation:
Methane is CH₄, the simplest alkane with one carbon atom bonded to four hydrogen atoms. The series general formula is CₙH₂ₙ₊₂. For n=1, H=4. CH, CH₂, CH₃ are not stable neutral molecules; they are fragments (methyl radical etc.). Methane is a major component of natural gas and biogas.

Explanation:
pH = -log[H⁺] = -log(10⁻⁴) = 4. The solution is acidic. pOH = 14 - pH = 10, so [OH⁻] = 10⁻¹⁰ M. pH scale ranges 0-14 (typically). pH < 7 acidic, pH = 7 neutral, pH > 7 basic. Pure water has [H⁺] = 10⁻⁷ M, pH=7.