A Pascal
B Bar
C Atmosphere
D Torr
Explanation: The Pascal (Pa) is the SI unit of pressure, equal to one newton per square meter.
A But-2-ene
B Ethene
C But-1-ene
D Ethyne
Explanation: But-2-ene exhibits cis-trans isomerism because each carbon of the double bond has different substituents.
Explanation: Nitrous oxide (N2O) is called laughing gas because it produces euphoria when inhaled.
A CO2 and water
B CO and water
C CO2 and hydrogen
D CO and hydrogen
Explanation: Complete combustion of any hydrocarbon in excess oxygen always yields CO2 and H2O.
A Propan-1-ol
B Propan-2-ol
C Butan-2-ol
D 2-Methylpropan-2-ol
Explanation: In propan-1-ol the hydroxyl group is attached to a carbon bonded to only one other carbon atom.
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.