The oxidation state of Cr in potassium dichromate (K2Cr2O7) is: MCQ with Answer and Explanation

Explanation:
Nuclear fission is a reaction in which the nucleus of a heavy atom (like Uranium-235 or Plutonium-239) splits into two or smaller, lighter nuclei when bombarded by a neutron, releasing a massive amount of energy and more neutrons, potentially causing a chain reaction.

Explanation:
Camphor sublimes—it directly changes from solid to vapor on heating without passing through the liquid phase. Other sublimable solids include naphthalene, iodine, ammonium chloride, and dry ice (solid CO₂). Sodium chloride, sugar, and sand melt or decompose on strong heating. Sublimation is used to separate sublimable substances from non-sublimable impurities. The process requires careful heating.

Explanation:
Chemical properties describe a substance's ability to undergo chemical changes—reactivity with acid, flammability, oxidation states, etc. Melting point, density, boiling point are physical properties that can be observed without changing composition. Reactivity with acid involves formation of new substances. A piece of magnesium reacting with HCl is a chemical change.