During electrolysis of water, hydrogen is liberated at: MCQ with Answer and Explanation

Explanation:
Covalent bonds are formed by the sharing of electrons, which typically occurs between two non-metal atoms that have high electronegativities and a tendency to gain electrons. Metals tend to lose electrons, forming ionic bonds with non-metals. Noble gases are generally inert and do not form bonds.

Explanation:
A small amount of ethanol (alcohol) is added to chloroform to inhibit its oxidation by air to toxic phosgene (COCl₂) and HCl. Ethanol acts as a negative catalyst (stabilizer) by consuming any formed phosgene. MnO₂, Pt, Fe are positive catalysts. Negative catalysts are also called inhibitors, used to prevent undesirable reactions.

Explanation:
Calorific value is the energy released per unit mass or volume of fuel. Common units: kJ/kg, kJ/g, J/g, kcal/kg, Btu/lb. It measures fuel efficiency. Hydrogen has about 141.9 MJ/kg (higher), petrol ~47 MJ/kg. Temperature (°C) is not a unit for calorific value. Pressure and concentration are not appropriate.