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Chemistry
A. An ester
B. An amide (N-methylacetamide)
C. A ketone
D. An ether
Answer: CH3NH2 (methylamine) reacts with CH3COOH (ethanoic acid) in a condensation reaction to form N-methylacetamide (CH3CONHCH3) and water.
Chemistry
A. 4
B. 6
C. 8
D. 2
Answer: In a tetrahedral complex, the metal is surrounded by 4 ligands at the corners of a tetrahedron, giving a coordination number of 4.
Chemistry
A. Increases K
B. Decreases K
C. Does not change K
D. Makes K zero
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).
Chemistry
A. Ethane
B. Ethanal (acetaldehyde)
C. Ethanoic acid
D. Ethyl acetate
Answer: Mild oxidation of ethanol with acidified K2Cr2O7 produces ethanal (acetaldehyde). With excess oxidant and heating, it further oxidizes to ethanoic acid.
Chemistry
A. s-s overlap
B. p-p overlap
C. sp-sp overlap
D. s-p overlap
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).
Chemistry
A. IR spectroscopy
B. NMR spectroscopy
C. Mass spectrometry
D. UV-Vis spectroscopy
Answer: Mass spectrometry ionizes molecules and measures the mass-to-charge ratio (m/z), providing precise molecular mass and structural fragmentation patterns.
Chemistry
A. K = kf + kr
B. K = kf / kr
C. K = kr / kf
D. K = kf x kr
Answer: At equilibrium, forward rate equals reverse rate: kf[reactants] = kr[products], so K = [products]/[reactants] = kf/kr.
Chemistry
A. Kc = [SO3]^2 / ([SO2]^2 x [O2])
B. Kc = [SO2]^2 x [O2] / [SO3]^2
C. Kc = [SO3] / ([SO2] x [O2])
D. Kc = [SO3]^2 / [SO2]^2
Answer: Kc = [products]^coefficients / [reactants]^coefficients = [SO3]^2 / ([SO2]^2 x [O2]^1).
Chemistry
A. 2-Methylbutanoic acid
B. 3-Methylbutanoic acid
C. 2-Ethylpropanoic acid
D. 2-Methylpentanoic acid
Answer: The longest chain containing COOH has 4 carbons (butanoic acid). Numbering from COOH, the methyl is on C3, giving 3-methylbutanoic acid.
Chemistry
A. A nitrile
B. A cyanohydrin (2-hydroxybutanenitrile)
C. An amide
D. An oxime
Answer: HCN adds across the C=O bond of propanal: the CN- attacks the carbonyl carbon and H+ protonates the oxygen, forming a cyanohydrin.
Chemistry
A. Free radical mechanism coupling alkyl halides
B. Nucleophilic substitution
C. Electrophilic addition
D. Elimination
Answer: The Wurtz reaction uses sodium metal to couple two alkyl halide molecules via a free radical mechanism: 2R-X + 2Na -> R-R + 2NaX.
Chemistry
A. Polyethylene
B. Polyvinyl chloride
C. Polylactic acid (PLA)
D. Polystyrene
Answer: PLA is a biodegradable polyester derived from lactic acid (from corn starch). Microorganisms can break down its ester linkages in the environment.
Chemistry
A. Addition of a diene to an alkene forming a six-membered ring
B. Elimination reaction forming a conjugated system
C. Nucleophilic substitution on a diene
D. Radical polymerization of dienes
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.
Chemistry
A. Tetrahedral
B. Square planar
C. Octahedral
D. Trigonal bipyramidal
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.
Chemistry
A. KMnO4
B. SOCl2 (thionyl chloride)
C. Na2Cr2O7
D. NaOH
Answer: SOCl2 converts alcohols to alkyl chlorides with inversion of configuration (if chiral). The byproducts SO2 and HCl are gases, driving the reaction forward.
Chemistry
A. Covalent bond energy
B. Lattice energy of ionic compounds
C. Ionization energy of metals
D. Electron affinity of nonmetals
Answer: The Born-Haber cycle applies Hess\'s law to calculate lattice energy by combining steps: sublimation, ionization, dissociation, electron affinity, and formation.
Chemistry
A. Temperature and pressure of a gas
B. Absorbance to concentration, path length, and molar absorptivity
C. Rate of reaction to concentration
D. Voltage to current and resistance
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.
Chemistry
A. Formaldehyde
B. Acetaldehyde
C. Acetone
D. Acetic acid
Answer: CH3COCH3 (propan-2-one) is commonly known as acetone, the simplest ketone and an important industrial solvent.
Chemistry
A. Bromination of benzene with Br2/FeBr3
B. Chlorobenzene reacting with NaOH at high temperature
C. Friedel-Crafts alkylation of benzene
D. Nitration of benzene
Answer: Chlorobenzene reacts with NaOH at high T/pressure (Dow process) via nucleophilic aromatic substitution, where OH- replaces Cl on the aromatic ring.
Chemistry
A. [Ar] 3d4 4s2
B. [Ar] 3d5 4s1
C. [Ar] 3d6 4s0
D. [Ar] 3d3 4s2 4p1
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.