A 6, 8, 6
B 6, 6, 8
C 8, 6, 6
D 6, 14, 6
Explanation: Carbon-14 has 6 protons, 14 - 6 = 8 neutrons, and 6 electrons (neutral atom).
A Zero
B 1 kJ/mol
C -1 kJ/mol
D Depends on the element
Explanation: By convention, the standard enthalpy of formation of an element in its most stable form is zero.
A CH2=CH2 + H2 to CH3CH3
B CH4 + Cl2 to CH3Cl + HCl
C 2CH3CH2OH to CH3CH2OCH2CH3 + H2O
D CH3COOH + NaOH to CH3COONa + H2O
Explanation: In this reaction, hydrogen adds across the double bond of ethene to form ethane.
A [Ar] 3d6
B [Ar] 3d5
C [Ar] 3d4
D [Ar] 3d6 4s2
Explanation: Fe has configuration [Ar] 3d6 4s2; losing 2 electrons from 4s gives [Ar] 3d6.
A Increases down the group
B Decreases down the group
C Remains constant
D First increases then decreases
Explanation: Atomic radius increases down a group because new electron shells are added at each period.
A H2SO4
B H2S
C SO2
D SCl2
Explanation: Sulfuric acid (H2SO4) is an oxoacid because it contains oxygen, hydrogen, and sulfur.
A 2, 8, 2
B 2, 8, 1
C 2, 8, 7
D 2, 7, 1
Explanation: Sodium has 11 electrons arranged as 2, 8, 1 giving it one valence electron.
A Sodium
B Chlorine
C Oxygen
D Argon
Explanation: Chlorine is a halogen and belongs to Group 17 of the periodic table.
A Acetic acid
B Hydrochloric acid
C Carbonic acid
D Phosphoric acid
Explanation: Hydrochloric acid (HCl) completely ionizes in water, making it a strong acid.
A Sugar solution
B Sodium chloride solution
C Distilled water
D Ethanol
Explanation: Sodium chloride solution conducts electricity because it dissociates into Na+ and Cl- ions.
A Melting
B Sublimation
C Condensation
D Evaporation
Explanation: Sublimation is the phase transition where a solid changes directly into gas without becoming liquid.
A NaCl
B CCl4
C KBr
D MgO
Explanation: CCl4 is formed by sharing electrons between carbon and chlorine atoms, making it covalent.
A Increase in temperature
B Decrease in temperature
C Increase in pressure only
D No change
Explanation: Gas solubility in water increases as temperature decreases because kinetic energy of gas molecules reduces.
A Vanadium pentoxide
B Iron
C Platinum
D Manganese dioxide
Explanation: Iron is used as a catalyst in the Haber process for the synthesis of ammonia from N2 and H2.
A 2, 8, 7
B 2, 8, 8
C 2, 8, 6
D 2, 7, 8
Explanation: Chlorine gains one electron to form Cl-, giving it 18 electrons arranged as 2, 8, 8 like argon.
A Electron affinity
B Ionization energy
C Electronegativity
D Lattice energy
Explanation: Ionization energy is the minimum energy required to remove the most loosely bound electron from a gaseous atom.
A Methanoic acid
B Ethanoic acid
C Propanoic acid
D Ethanal
Explanation: CH3COOH has a two-carbon chain with a carboxyl group, giving it the IUPAC name ethanoic acid.
A 0.5 mole
B 1 mole
C 2 moles
D 1.5 moles
Explanation: CaCO3 to CaO + CO2 is a 1:1 reaction, so 1 mole produces 1 mole of CO2.
Explanation: KMnO4 contains Mn in +7 oxidation state and readily accepts electrons, making it a strong oxidizing agent.
A 11.2 L
B 22.4 L
C 44.8 L
D 2.24 L
Explanation: At standard temperature and pressure, 1 mole of an ideal gas occupies 22.4 L.