A Roasting
B Smelting
C Cyanide process
D Electrolysis
Explanation: Gold is extracted by dissolving in dilute NaCN solution (cyanide process) followed by reduction.
Explanation: Xe in XeF4 has 8 valence electrons, uses 4 for bonding and has 2 lone pairs remaining.
A Nitrosobenzene
B Aniline
C Phenol
D Benzoic acid
Explanation: Sn/HCl reduces the nitro group of nitrobenzene to an amino group, producing aniline.
Explanation: Nitrogen in NH4+ forms four equivalent sigma bonds with hydrogen using sp3 hybridization.
A Photosynthesis
B Melting of ice
C Evaporation of water
D Combustion of methane
Explanation: Combustion of methane releases heat energy, making it an exothermic process.
Explanation: A neutral solution has equal concentrations of H+ and OH- ions, giving a pH of 7.
A Linear
B Trigonal planar
C Tetrahedral
D Trigonal pyramidal
Explanation: NH3 has three bonding pairs and one lone pair on nitrogen, giving a trigonal pyramidal shape.
A Decrease in temperature
B Increase in concentration
C Increase in particle size
D Stronger van der Waals forces
Explanation: Boiling point increases with molecular weight in alkanes due to stronger van der Waals forces.
A London dispersion
B Hydrogen bonding
C Ionic bonding
D Dipole-dipole interactions
Explanation: HCl is polar without H bonded to N, O, or F, so dipole-dipole forces are dominant.
Explanation: In K2Cr2O7, 2(+1) + 2x + 7(-2) = 0, solving gives x = +6 for chromium.
A 180 degrees
B 120 degrees
C 109.5 degrees
D 104.5 degrees
Explanation: Water has a bent shape with two lone pairs on oxygen that compress the angle to about 104.5 degrees.
A They are highly reactive
B They form covalent compounds
C They have high ionization energies
D They have weak van der Waals forces
Explanation: Noble gases have low boiling points due to weak van der Waals forces between their atoms.
A Addition
B Elimination
C Condensation
D Substitution
Explanation: Chlorine replaces hydrogen atoms in methane via a free radical substitution mechanism.
Explanation: N2 has all paired electrons in its molecular orbitals, making it diamagnetic.
A Propan-1-ol
B 2-Methylpropan-1-ol
C Butan-2-ol
D Propan-2-ol
Explanation: The hydroxyl group is on carbon 2 of a three-carbon chain, giving propan-2-ol.
A Ethanoic acid
B Ethene
C Ethyl acetate
D Ethanal
Explanation: Acidified K2Cr2O7 is a mild oxidizing agent that oxidizes ethanol to ethanal under distillation.
A [Ar] 3d9 4s2
B [Ar] 3d8 4s2
C [Ar] 3d10 4s2
D [Ar] 3d10 4s1
Explanation: Copper has an anomalous configuration [Ar] 3d10 4s1 due to the stability of a fully filled 3d subshell.
A CH4
B C2H6
C C3H8
D C4H10
Explanation: Boiling point increases with molecular weight in alkanes due to stronger van der Waals forces.
A Dilute H2SO4
B Dilute HCl
C Dilute HNO3
D Concentrated H2SO4
Explanation: Concentrated H2SO4 has a strong affinity for water and is widely used as a dehydrating agent.
A Litmus test
B Baeyer\'s test
C Fehling\'s test
D Tollen\'s test
Explanation: Tollen\'s reagent oxidizes aldehydes but not ketones, producing a silver mirror with aldehydes.