Which allotrope of carbon is used as a neutron moderator in nuclear reactors? MCQ with Answer and Explanation

Explanation:
Brittleness is a property typical of non-metals and metalloids; metals are ductile and malleable, not brittle. Ductility: drawn into wires (gold most ductile). Malleability: beaten into sheets (gold most malleable). Metals also have luster, high thermal and electrical conductivity, and sonorous nature. Brittle substances break easily under stress without significant deformation (e.g., glass, sulfur). Some metals like cast iron are brittle but generally pure metals are not.

Explanation:
Tricalcium aluminate (C₃A) reacts quickly with water and is responsible for the flash setting of cement. Gypsum is added to control the rate of this initial set. Tricalcium silicate (C₃S) provides early strength. Dicalcium silicate (C₂S) gives later strength. Tetracalcium aluminoferrite (C₄AF) contributes to color and hardness. Cement composition is abbreviated in cement chemistry notation.

Explanation:
Oxidation is the gain of oxygen or loss of electrons. Here, Carbon (C) gains oxygen to form Carbon dioxide (CO₂), so Carbon is oxidized. Lead oxide (PbO) loses oxygen to form Lead (Pb), so PbO is reduced. This is a classic redox reaction where both processes occur simultaneously.