Chemistry MDCAT MCQs
Organic, inorganic & physical chemistry MCQs
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Answer: In a tetrahedral complex, the metal is surrounded by 4 ligands at the corners of a tetrahedron, giving a coordination number of 4.
Answer: PLA is a biodegradable polyester derived from lactic acid (from corn starch). Microorganisms can break down its ester linkages in the environment.
Answer: At equilibrium, forward rate equals reverse rate: kf[reactants] = kr[products], so K = [products]/[reactants] = kf/kr.
Answer: The Wurtz reaction uses sodium metal to couple two alkyl halide molecules via a free radical mechanism: 2R-X + 2Na -> R-R + 2NaX.
Answer: HCN adds across the C=O bond of propanal: the CN- attacks the carbonyl carbon and H+ protonates the oxygen, forming a cyanohydrin.
Answer: SOCl2 converts alcohols to alkyl chlorides with inversion of configuration (if chiral). The byproducts SO2 and HCl are gases, driving the reaction forward.
267
What is the formula for the equilibrium constant Kc for the reaction: 2SO2(g) + O2(g) <=> 2SO3(g)?
Answer: Kc = [products]^coefficients / [reactants]^coefficients = [SO3]^2 / ([SO2]^2 x [O2]^1).
Answer: CH3COCH3 (propan-2-one) is commonly known as acetone, the simplest ketone and an important industrial solvent.
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).
270
What is the geometry of a d8 metal complex with a strong field ligand in square planar arrangement?
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: The longest chain containing COOH has 4 carbons (butanoic acid). Numbering from COOH, the methyl is on C3, giving 3-methylbutanoic acid.
Answer: Mass spectrometry ionizes molecules and measures the mass-to-charge ratio (m/z), providing precise molecular mass and structural fragmentation patterns.
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: Mild oxidation of ethanol with acidified K2Cr2O7 produces ethanal (acetaldehyde). With excess oxidant and heating, it further oxidizes to ethanoic 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).
Answer: The Born-Haber cycle applies Hess\'s law to calculate lattice energy by combining steps: sublimation, ionization, dissociation, electron affinity, and formation.
Answer: CH3NH2 (methylamine) reacts with CH3COOH (ethanoic acid) in a condensation reaction to form N-methylacetamide (CH3CONHCH3) and water.
Answer: Chlorobenzene reacts with NaOH at high T/pressure (Dow process) via nucleophilic aromatic substitution, where OH- replaces Cl on the aromatic ring.
Answer: Chromium is an exception: one 4s electron promotes to 3d to achieve the extra stability of half-filled d-orbitals, giving [Ar] 3d5 4s1.
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.