Glass is made by heating sand with: MCQ with Answer and Explanation

Explanation:
Complete combustion of ethanol: C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O + heat. In sufficient oxygen, carbon burns to CO₂, hydrogen to H₂O. Incomplete combustion (lack of O₂) produces CO and soot (C). Ethanol is a biofuel, reducing CO₂ emissions if derived from biomass. It has high octane number and is blended with petrol (gasohol). CO₂ is a greenhouse gas, but bioethanol is carbon-neutral over cycle.

Explanation:
Ionization energy (IE) is the minimum energy needed to remove an electron from an isolated gaseous atom in its ground state to form a cation. A(g) → A⁺(g) + e⁻. Adding an electron is electron affinity. IE is an indicator of reactivity. Metals have low IE, non-metals high IE.

Explanation:
NaOH is a strong base; it dissociates to give OH⁻ ions, making the solution basic (pH >7). Bases turn red litmus blue. Acids turn blue litmus red.