Which of the following molecules has a linear shape?
A. CH₄
B. CO₂
C. NH₃
D. H₂O
Answer: Option B
Solution (By JKSSB Mock Tests)
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.
Explanation:
Ernest Rutherford discovered the atomic nucleus through his gold foil experiment (1911). J.J. Thomson discovered the electron (1897). Chadwick discovered the neutron (1932). Bohr proposed the model of the atom with quantized energy levels (1913), not the electron. Rutherford also discovered the proton (1919). Naming discoveries correctly is important for competitive exams.
Explanation:
Methanol (CH₃OH) was historically produced by destructive distillation of wood, hence called wood alcohol. Ethanol is grain alcohol (from fermentation). Rubbing alcohol is isopropanol or denatured ethanol. Denatured alcohol is ethanol with added methanol or other substances to make it undrinkable. Methanol is toxic, used as solvent, fuel, and antifreeze.
Explanation:
Neutron has mass approximately equal to proton (1.675 × 10⁻²⁷ kg) and no electric charge. Proton mass ~1.673 × 10⁻²⁷ kg, positive charge. Electron mass ~9.11 × 10⁻³¹ kg, negative charge. Positron is the antiparticle of electron, same mass, positive charge. Neutron's neutrality makes it important for nuclear stability.
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