Chemistry — Mixed Practice — Part 1: 40 MCQs with Explanations

Boyle's law: For fixed amount of gas at constant temperature, pressure is inversely proportional to volume: PV = constant.

Longest carbon chain has 5 atoms (pentane) with a methyl group at position 3: 3-methylpentane.

Ethylene glycol (HO-CH₂-CH₂-OH) lowers freezing point of water significantly, making it ideal as antifreeze in automobile radiators.

For zero-order: rate = k, so units of k = units of rate = mol L⁻¹ s⁻¹.

For first-order: t½ = 0.693/k → k = 0.693/30 = 0.0231 min⁻¹.

NH₃ shows maximum deviation due to strong intermolecular forces (hydrogen bonding) and relatively large molecular size.

In homologous series, boiling point increases with molecular weight due to stronger London dispersion forces.

Ionization energy generally increases across a period (left to right) due to increasing nuclear charge and decreases down a group due to increasing atomic size.

2-Chlorobutane (CH₃CH₂CHClCH₃) has a chiral carbon (C2 bonded to H, Cl, CH₃, CH₂CH₃), so it is optically active.

Ethylamine (C₂H₅NH₂) has -NH₂ group attached to one alkyl group, making it primary amine.

FCC: 8 corners × 1/8 = 1 atom + 6 faces × 1/2 = 3 atoms → total 4 atoms.

CO₂ absorbs infrared radiation, contributing to greenhouse effect. O₂, N₂, Ar are not greenhouse gases.

Compounds with CH₃CH(OH)- or CH₃CO- groups give iodoform test. Ethanol, acetaldehyde, and acetone all give this test.

Saponification is alkaline hydrolysis of esters (fats/oils) to produce soap and glycerol.

Using Arrhenius: ln(2) = (Ea/R)(1/300 - 1/310). 0.693 = (Ea/8.314)(0.0001075). Ea ≈ 53.6 kJ/mol.

tert-Butyl chloride ((CH₃)₃CCl) has Cl attached to carbon bonded to three other carbons.

Cubic system: all sides equal (a=b=c) and all angles 90°.

Ethene undergoes electrophilic addition with bromine, decolorizing bromine water.

pH = -log(5×10⁻⁴) = 4 - log5 = 4 - 0.70 = 3.30.

Butan-2-ol (CH₃CH₂CHOHCH₃) has chiral carbon and exists as enantiomers.

This reaction represents formation of CO₂ from elements in standard states, so ΔH = ΔHf°(CO₂) = -393.5 kJ/mol.

HF has highest bp due to hydrogen bonding. Order: HCl (-85°C) < HBr (-67°C) < HI (-35°C) < HF (19.5°C).

BCC: 8 corners × 1/8 = 1 atom + 1 body center × 1 = 1 atom → total 2 atoms.

Benzaldehyde lacks α-hydrogen, so it does not show keto-enol tautomerism.

Vanadium pentoxide (V₂O₅) is used as catalyst in contact process: 2SO₂ + O₂ ⇌ 2SO₃.

BeCl₂ has linear geometry (180°) with sp hybridization.

Tertiary carbocation is most stable due to hyperconjugation and inductive effects.

E°cell = E°cathode - E°anode = 0.80 - (-0.76) = 1.56 V.

Longest chain: 5 carbons (pentane). Methyl groups at positions 2,2,4: 2,2,4-trimethylpentane (isooctane).

Lactose has free anomeric carbon in glucose unit, making it reducing sugar.

Phenol has strongly activating -OH group, making ring highly reactive toward electrophilic substitution.

CsCl has body-centered cubic structure with coordination number 8.

Nitrobenzene strongly deactivates ring and coordinates with AlCl₃ catalyst, preventing Friedel-Crafts reactions.

Glucose is a monosaccharide with molecular formula C₆H₁₂O₆.

Finely divided nickel is commonly used as catalyst for hydrogenation of vegetable oils to produce vanaspati ghee.

Chlorofluorocarbons (CFCs) release chlorine radicals in stratosphere that catalyze ozone destruction.

Chlorofluorocarbons (CFCs) were traditionally used as refrigerants (though being phased out due to ozone depletion).

Carbon dioxide is a major greenhouse gas that traps heat in Earth's atmosphere.

Silver halides (AgCl, AgBr, AgI) are light-sensitive and used in photographic films and papers.

Sucrose (glucose + fructose) is a disaccharide. Glucose and fructose are monosaccharides; starch is a polysaccharide.