Graham's law of diffusion relates rate of diffusion to: MCQ with Answer and Explanation

Explanation:
In BF₃, boron has 3 valence electrons and forms 3 covalent bonds with fluorine, resulting in only 6 electrons in its valence shell. It does not complete its octet, making it an electron-deficient molecule and a strong Lewis acid. NH₃, H₂O, and CH₄ all have complete octets.

Explanation:
In the Contact process, the key catalytic step is oxidation of SO₂ to SO₃ using V₂O₅ (vanadium pentoxide) catalyst at 450°C: 2SO₂ + O₂ ⇌ 2SO₃. Sulfur burning is non-catalytic. The SO₃ is absorbed in 98% H₂SO₄ to form oleum (H₂S₂O₇), then diluted to get concentrated H₂SO₄. Direct dissolution of SO₃ in water is avoided due to mist formation.

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.