Which of the following is an example of green chemistry? MCQ with Answer and Explanation

Explanation:
Graphite mixed with clay forms pencil 'lead'. Its layered structure marks paper. Diamond is used in cutting, fullerene in nanotechnology, charcoal in filters and fuel.

Explanation:
James Chadwick discovered the neutron in 1932 by bombarding beryllium with alpha particles, producing a neutral radiation that he identified as neutrons. Rutherford had predicted the existence of a neutral particle in 1920. Chadwick's discovery explained isotopes' mass differences. Neutron: mass ≈ 1.00866 u, no charge. It is stable inside the nucleus but decays (half-life ~10 min) when free.

Explanation:
CO₂ has sp hybridized carbon, forming two double bonds with oxygen in a linear arrangement (O=C=O) with bond angle 180°. H₂O is bent (angular, 104.5°), NH₃ is trigonal pyramidal (107°), CH₄ is tetrahedral (109.5°). Molecular shape is determined by VSEPR theory: CO₂ has 2 bond pairs, 0 lone pairs → linear.