The Magical Mole Concept
MCQ:
Which of the following represents the number of particles in one mole of any substance?
(a) 1.0 x 1023
(b) 6.02 x 1023
(c) 12.0 x 1024
(d) 6.02 x 10-23
b) 6.02×1023
This is Avogadro's constant, which defines the number of particles (atoms, molecules, ions) in one mole. .
MCQ:
Which homologous series contains a triple bond between carbon atoms?
(a) Alkynes
(b) Alkenes
(c) Alkanes
(d) Alcohols
(a) Alkynes
Alkynes are unsaturated hydrocarbons that contain at least one carbon-carbon triple bond (C≡C).
MCQ:
A reaction that releases heat energy to the surroundings is classified as:
(a) Endothermic
(b) Neutral
(c) Exothermic
(d) Catalytic
(c) Exothermic
Exothermic reactions release energy, usually as heat, causing the temperature of the surroundings to rise (Delta H is negative).
True/False:
Oxidation is the gain of electrons.
False.
Oxidation is the loss of electrons (OIL: Oxidation Is Loss of electrons). Reduction is the gain of electrons (RIG).
MCQ:
What is the primary role of chlorine in the final stage of water treatment?
(a) To soften the water
(b) To act as a flocculant
(c) To filter out solid particles
(d) To kill bacteria
(d) To kill bacteria
Chlorination is the process of adding chlorine to water to act as a disinfectant, effectively killing harmful bacteria and microorganisms.
Fill in the Blank:
The mass of one mole of a substance is called its ....... mass.
(a) Relative Atomic
(b) Relative Molecular
(c) Molar
(d) Equivalent
(c) Molar
The Molar mass is the mass in grams of one mole of a substance (units are g mol−1).
True/False:
The general formula for the alkane series is CnH2n+2.
True
This formula applies to all straight-chain and branched-chain alkanes.
Fill in the Blank:
The minimum energy required to start a chemical reaction is called the energy.
(a) Bond
(b) Enthalpy
(c) Kinetic
(d) Activation
(d) Activation
Activation energy (Ea) is the energy barrier that must be overcome for reactants to transform into products.
Fill in the Blank:
In an electrochemical cell, the electrode where reduction occurs is called the .........
(a) Anode
(b) Cathode
(c) Electrolyte
(d) Salt Bridge
(b) Cathode
Reduction always occurs at the Cathode (RED CAT). Oxidation always occurs at the Anode (AN OX).
Fill in the Blank:
Acid rain is primarily caused by the atmospheric presence of oxides of Sulfur and .............
(a) Carbon
(b) Nitrogen
(c) Silicon
(d) Phosphorus
(b) Nitrogen
Sulfur Dioxide (SO2) and Nitrogen Oxides (NOx) dissolve in rainwater to form sulfuric acid and nitric acid, respectively, causing acid rain.
True/False:
True or False: At standard temperature and pressure (STP), 1 mole of any gas occupies a volume of 24 dm3
False. At STP, 1 mole of any gas occupies 22.4 dm3. The 24 dm3 value is used for Room Temperature and Pressure (RTP).
Fill in the Blank:
A molecule with the same molecular formula but a different structural formula is called an ............. .
(a) Isomer
(b) Allotrope
(c) Polymer
(d) Homologue
(a) Isomer
Isomers are compounds that have the same molecular formula but a different arrangement of atoms in space, leading to different structural formulae and properties.
True/False:
Increasing the concentration of reactants increases the rate of reaction.
True
Higher concentration means more particles per unit volume, leading to a greater frequency of effective collisions, thus increasing the reaction rate.
True/False:
A more reactive metal can displace a less reactive metal from a solution of its salt.
True.
The more reactive metal is a stronger reducing agent and will be preferentially oxidized, thus displacing the ions of the less reactive metal.
Fill in the Blank:
The chemical added in water treatment that causes small suspended particles to clump together is a .
(a) Disinfectant
(b) Flocculant
(c) Softener
(d) Deodorizer
(b) Flocculant
A Flocculant (like Aluminium Sulfate) causes the tiny particles to aggregate into larger clumps (flocs), which can then be settled or filtered out.
MCQ:
What is the mass of 0.5 mol of water H2O (Given H=1, O= 16).
(a) 18 g
(b) 9 g
(c) 1 g
(d) 0.5 g
(b) 9 g
Molar Mass of H2O= (2 x 1) + 16 = 18 g mol-1. Mass = Moles x Molar Mass = 0.5 x 18 = 9 g.
MCQ
Ethene (C2H4) reacts with bromine water, turning it from orange to colourless. This is an example of a(n):
(a) Substitution reaction
(b) Neutralisation reaction
(c) Condensation reaction
(d) Addition reaction
(d) Addition reaction
Addition reactions are characteristic of unsaturated hydrocarbons (like alkenes) where atoms are added across the double bond, which is the basis for the test for unsaturation.
MCQ
Which of the following factors is NOT generally considered when studying reaction kinetics?
(a) Atomic Mass
(b) Pressure
(c) Surface Area
(d) Temperature
(a) Atomic Mass
Atomic Mass of the elements is a property of the substance, but does not directly influence the rate at which the reaction occurs.
Fill in the Blank:
............... is the process of coating an object with a thin layer of metal using electrolysis.
(a) Galvanizing
(b) Electroplating
(c) Anodizing
(d) Purification
(b) Electroplating
Electroplating is the deposition of a metal layer onto another surface by reduction at the cathode in an electrolytic cell.
True/False:
Smog is a type of air pollution often formed by the reaction of sunlight with vehicle exhaust fumes.
True.
Photochemical smog is a complex mixture of pollutants, often formed when sunlight reacts with nitrogen oxides and volatile organic compounds from car exhausts.
True/False:
1 dm3 is equal to 1000 cm3.
True
Volume conversions are important in mole calculations. 1 dm3 is equal to 1000 cm3
True/False:
Saturated hydrocarbons contain only single carbon-carbon bonds.
True
Saturated means the molecule has the maximum number of hydrogen atoms possible, and thus only single C-C bonds (Alkanes).
Fill in the Blank:
A substance that increases the rate of a chemical reaction but is chemically unchanged at the end is a ............
(a) Inhibitor
(b) Catalyst
(c) Oxidizing Agent
(d) Reactant
(b) Catalyst
Catalyst provides an alternative reaction pathway with a lower activation energy, speeding up the reaction.
MCQ:
Which of the following is NOT a common use of electrolysis?
(a) Extraction of reactive metals
(b) Purification of copper
(c) Manufacture of Sulfuric Acid
(d) Electroplating
(c) Manufacture of Sulfuric Acid
Sulfuric Acid is manufactured by the Contact Process, which is a chemical process and does not use electrolysis.
True/False:
The Haber Process is used for the large-scale manufacture of Sulfuric Acid.
False.
The Haber Process is used for the large-scale manufacture of Ammonia (NH3). The Contact Process is used for Sulfuric Acid.