Science Group
Explore subjects and practice MCQs
7
Chapters
1,610
Total MCQs
Science Group
Answer: Delta G0 = -RT ln K. When K = 1, ln K = 0, so Delta G0 = 0. The standard state has equal free energies of reactants and products.
Answer: In an octahedral field, the five d-orbitals split into two sets: t2g (dxy, dxz, dyz, lower energy) and eg (dz2, dx2-y2, higher energy), separated by Delta_o.
Answer: XeO3 has three Xe=O bonds and one lone pair on Xe (3 bonding pairs + 1 lone pair = 4 electron domains), giving sp3 hybridization with trigonal pyramidal geometry.
Answer: A second-order reaction has Rate = k[A]^2 (or Rate = k[A][B]). The half-life t1/2 = 1/(k[A]0) depends on initial concentration, and a plot of 1/[A] vs time is linear.
Answer: The Wittig reaction converts a carbonyl (C=O) to an alkene (C=C) using a phosphonium ylide (Wittig reagent), forming a phosphine oxide byproduct.
Answer: The Born-Haber cycle applies Hess\'s law to calculate lattice energy by combining steps: sublimation, ionization, dissociation, electron affinity, and formation.
Answer: The Diels-Alder reaction is a [4+2] cycloaddition between a conjugated diene (4 pi electrons) and a dienophile (2 pi electrons), forming a cyclohexene ring.
Answer: At equilibrium, forward rate equals reverse rate: kf[reactants] = kr[products], so K = [products]/[reactants] = kf/kr.
Answer: CH3COCH3 (propan-2-one) is commonly known as acetone, the simplest ketone and an important industrial solvent.
Answer: Mass spectrometry ionizes molecules and measures the mass-to-charge ratio (m/z), providing precise molecular mass and structural fragmentation patterns.
Answer: Mild oxidation of ethanol with acidified K2Cr2O7 produces ethanal (acetaldehyde). With excess oxidant and heating, it further oxidizes to ethanoic acid.
572
Answer: d8 metals (like Ni2+, Pd2+, Pt2+) with strong field ligands form square planar complexes because the large crystal field splitting makes this geometry more stable than tetrahedral.
Answer: Beer-Lambert Law states absorbance (A) = molar absorptivity (epsilon) x path length (l) x concentration (c), forming the basis of quantitative UV-Vis analysis.
Answer: Chlorobenzene reacts with NaOH at high T/pressure (Dow process) via nucleophilic aromatic substitution, where OH- replaces Cl on the aromatic ring.
575
Answer: Kc = [products]^coefficients / [reactants]^coefficients = [SO3]^2 / ([SO2]^2 x [O2]^1).
Answer: PLA is a biodegradable polyester derived from lactic acid (from corn starch). Microorganisms can break down its ester linkages in the environment.
Answer: CH3NH2 (methylamine) reacts with CH3COOH (ethanoic acid) in a condensation reaction to form N-methylacetamide (CH3CONHCH3) and water.
Answer: A catalyst speeds up both forward and reverse reactions equally by lowering activation energy. It helps reach equilibrium faster but does not change the position of equilibrium (K).
Answer: The longest chain containing COOH has 4 carbons (butanoic acid). Numbering from COOH, the methyl is on C3, giving 3-methylbutanoic acid.
Answer: In H2, each hydrogen has a 1s orbital. The sigma bond is formed by the head-on overlap of these two 1s orbitals (s-s overlap).