SS 3 CHEMISTRY PAST QUESTIONS (WAEC/NECO) HomeWAEC/NECO Exam Past QuestionsSS 3 CHEMISTRY PAST QUESTIONS (WAEC/NECO) 0% SSCE/NECO/GCE (CHEMISTRY PAST QUESTIONS) CHEMISTRY PAST QUESTIONS APP Questions will be picked at random from the question bank. You can use the NEXT button to move to the next question, use the PREV button to move to the previous question, the CLEAR button to clear any answer of your choice and you have the FINISH button to end the exam if you choose to. Any question not answered before the end of the exam time, will be marked as wrong and the exam will end by itself. so try to attempt all questions on time. Goodluck! 1 / 80 Category: CHEMISTRY PAST QUESTIONS Exhaust fumes discharged from a smoky vehicle gradually become invisible as a result of absorption combustion emission diffusion 2 / 80 Category: CHEMISTRY PAST QUESTIONS The spontaneity of a chemical reaction is determined by the change in the concentration of the reactants temperature of the system free energy of the system pressure applied to the system 3 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the orbitals 4s, 4p, 4d and 4f has the lowest energy? 4f 4p 4d 4s 4 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following is not correct about oxidation number convention? The oxidation number of a/an alkali meta like sodium in its compounds is + 1 element in the free state is zero atom of a diatomic molecules is + 2 monatomic ion is equal to its charge 5 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following contains co-ordinate covalent bond? HCI NH4 Na+CI CH4 6 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following lowers the activation energy of a chemical reaction? Reducing agent Catalyst Freezing mixture Water 7 / 80 Category: CHEMISTRY PAST QUESTIONS Two radioactive elements Q and S have half-life periods of 10 hours and 20 hours respectively. Therefore Q emits fewer particles than S S is more stable than Q S decays faster than Q Q is twice as stable as S 8 / 80 Category: CHEMISTRY PAST QUESTIONS Metals are said to be malleable because they are good conductors of electricity are good conductors heat can be beaten into sheets can be alloyed 9 / 80 Category: CHEMISTRY PAST QUESTIONS What will be the effect of increase in pressure on the following system at equilibrium? 2NH2(g) N2(g) + 3H2(g) the forward reaction will be favoured the concentration of ammonia will increase the reaction will go to completion Activation energy will decrease 10 / 80 Category: CHEMISTRY PAST QUESTIONS What is the effect of using vanadium (V) oxide as catalyst in the reaction represented by the following equation? 2SO2 + O2 ⇌ 2SO3; ∆H = - xKJmol-1 Increases the collision rate of reactant particles Decreases the value of ∆H Reduces the time for attainment of equilibrium Shifts equilibrium position to the right 11 / 80 Category: CHEMISTRY PAST QUESTIONS A reaction is represented by the equation below. A2(g) + B2(g) 2AB(g); ∆H = +X kJmol-1 Which of the following statements about the system is correct? The reaction goes to completion at equilibrium At equilibrium increase in temperature favours the reverse reaction Pressure has no effect on the equilibrium mixture The forward reaction is exthermic 12 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following pairs of reagents recat to produce hydrogen? Magnesium and dilute tetraoxosulphate (VI) acid Zinc and concentrated trioxonitrate (V) acid Copper and dilute hydrochloric acid Water and calcium dicarbide 13 / 80 Category: CHEMISTRY PAST QUESTIONS A finely divided from of a metal burns more readily in air than the rod from because the rod has higher molar mass different chemical properties protective oxide coating smaller surface area 14 / 80 Category: CHEMISTRY PAST QUESTIONS What volume of hydrogen is produced at s.t.p. When 2.60 g of zinc reacts with excess HCI according to the following equation? Zn(s) + 2HCI(aq) → ZnCI 2(aq) + H2(g) [Zn = 65; 1 mole of a gas occupies 22.4dm3 at s.t.p] 0.896dm 3 8.62dm 3 0.040dm 3 5.82dm 3 15 / 80 Category: CHEMISTRY PAST QUESTIONS Chemical equilibrium is attained when concentrations of the products are greater than those of the reactants reactants stop forming the products concentrations of the reactants and products remain constant reactants in the system are used up 16 / 80 Category: CHEMISTRY PAST QUESTIONS What is the function of sulphur (IV) oxide in the reaction represented by the following equation? SO 2(aq) + 2H2S(g) → 3S (s) + 2H 2O (l) Dehydrating agent Acid Oxidising agent Bleaching agent 17 / 80 Category: CHEMISTRY PAST QUESTIONS If the solubility of KHCO3 is 0.40 mole dm-3 4.0g 10.0g 40.0g 100.0g 18 / 80 Category: CHEMISTRY PAST QUESTIONS Dehydration of ethanol produces ethanal ethanoic acid ethene propan-1,2,3-triol 19 / 80 Category: CHEMISTRY PAST QUESTIONS Pauli Exclusion Principle is related to collision theory of reaction rates electronegativity values of elements quantum numbers of electrons reversiblility of equlibrium reactions 20 / 80 Category: CHEMISTRY PAST QUESTIONS Substances which absorb water from the atmosphere without dissolving in it are said to be insolube hygroscopic anhydrous hydrated 21 / 80 Category: CHEMISTRY PAST QUESTIONS The property of calcium chloride which makes it useful as a drying agent is that it is a strong electrolyte deliquescent ionic a normal salt 22 / 80 Category: CHEMISTRY PAST QUESTIONS A radioactive solid is best stored in a box lined with lead under ultraviolet light under paraffin oil in a cool, dark cupboard 23 / 80 Category: CHEMISTRY PAST QUESTIONS What does ∆H represent in the following equation ? Cl(g) + e- → CI- (g); ∆H = - 363 kJ mol-1 Heat of atomization Electron affinity lonization energy Dissociation energy 24 / 80 Category: CHEMISTRY PAST QUESTIONS What is oxidized in the reaction represented by the following equation? 3CU + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O Oxygen Copper Nitrogen Hydrogen 25 / 80 Category: CHEMISTRY PAST QUESTIONS Petrol consists mainly of alktanols alkanoates polymers hydrocarbons 26 / 80 Category: CHEMISTRY PAST QUESTIONS What type of reaction is involved when wood shavings produce a brown gas with concentrated HNO3? Redox reaction Dehydration Destructive distillation Nutralization 27 / 80 Category: CHEMISTRY PAST QUESTIONS Aluminium is extracted from magnetite cryolite cassiterite bauxite 28 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following can undergo both addition reactions and substitution reactions? Hexane Propene Pentane Benzene 29 / 80 Category: CHEMISTRY PAST QUESTIONS A sheet of paper is placed in the path of a beam from a radioactive source. The emissions that pass through the paper consist of alpha particles and gamma rays beta particles and gamma rays alpha and beta particles alpha particles only 30 / 80 Category: CHEMISTRY PAST QUESTIONS One mole of a compound M(HCO3)2 has a mass of 162g. Calculate the relative atomic mass of M. [H = 1, C =12, O = 16] 101 40 53 122 31 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following increases as boiling water changes to steam? activation energy number of molecules degree of disorder in the system temperature of the system 32 / 80 Category: CHEMISTRY PAST QUESTIONS An exothermic reaction is one which involves evolution of gas as it proceeds attainment of dynamic equilibrium positive change in value of enthalpy loss of heat to the surrounding 33 / 80 Category: CHEMISTRY PAST QUESTIONS Equal volumes of CO2 cnd CO at s.t.p have the same number of molecules density mass rate of diffusion 34 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following procedures is suitable for identifying the food colouring added to a pastry sample? The cathode becomes coated with copper The blue colour of the solution fades gradually Both electrodes gain electrons The anode increases in mass 35 / 80 Category: CHEMISTRY PAST QUESTIONS A mixture of calcium chloride and calcium trioxocarbonate (IV) in water can be separated by sublimation evaporation filtration distillation 36 / 80 Category: CHEMISTRY PAST QUESTIONS What is responsible for metallic bonding? Attraction between the atomic unclei and cloud of electrons transfer of electrons from one atom to another Sharing of electrons between the metal atoms Attraction between positive and negative ions 37 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following properties increases down a group in the Periodic Table? Electronegativity Ionization energy Atomic radius Electon affinity 38 / 80 Category: CHEMISTRY PAST QUESTIONS Rusting of iron is an example of redox reaction deliquescence decomposition displacement reaction 39 / 80 Category: CHEMISTRY PAST QUESTIONS Gas molecules are said to be perfectly elastic because the distances between them are negligible they move about in straight lines they collide without loss of energy the volume occupied by them is negligible 40 / 80 Category: CHEMISTRY PAST QUESTIONS 30cm3 pf hydrogen at s.t.p combine with 20cm3 of oxygen to form steam according to the following equation 2H2(g) + O2(g) → 2H2O(g). Calculate the total volume of the gaseous mixture at the end of the reaction 50cm cube 30cm cube 35cm cube 25cm cube 41 / 80 Category: CHEMISTRY PAST QUESTIONS Elements which belong to the same group in the Periodic Table are characterized by difference of +1 in the oxidation numbers of successive members difference of 14 atomic mass units between successive members presence of the same number of outermost electrons in the respective atoms presence of the same number of electron shells in the respective atoms 42 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following movements can be described as random motion? car travelling on a straight line planets going round the sun wheelbarrow being pushed gas molecules colliding in a flask 43 / 80 Category: CHEMISTRY PAST QUESTIONS What mass of copper would be deposited by a current of 1. 0 ampere passing for 965 seconds through copper (ll) tetraoxosulphate (IV) solution? [Cu = 63.5; 1F = 96500C] 18g 0.318g 0.635g 6.35g 44 / 80 Category: CHEMISTRY PAST QUESTIONS In the Periodic Table, the elements that loss electrons most readily belong to Group 111 A Group 1 A Group 11 A Group V11 A 45 / 80 Category: CHEMISTRY PAST QUESTIONS When alkanols react with sodium, the ga evolved is hydrogen methane ethyne oxygen 46 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following methods is suitable for the preparation of an insoluble salt? Action of an acid on a trioxocarbonate (IV) Action of an acid on a metal Double decomposition Neutralisation 47 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following statements about ideal gases is/are correct? I. The cohesive forces between their particles are negligible ll. The have no definite volume but occupy the volume of their containers III. They are not compressible IV. Their particles collide with loss of energy l, ll and lll only l and ll only l, ll, lll, and IV l only 48 / 80 Category: CHEMISTRY PAST QUESTIONS The atoms of four elements are represented as 20Q, 16R, 10S and 8T Which of the elements would be unreactive? T S R Q 49 / 80 Category: CHEMISTRY PAST QUESTIONS 0.10 mol dm-3 NaCI conducts electricity better than 0.10 mol dm-3 CH3COOH because the solution of NaCI has a higher pH contains more ions is neutral to litmus has a lower molar mass 50 / 80 Category: CHEMISTRY PAST QUESTIONS What is the oxidation number of nitrogen in AI(NO3)3? + 3 + 1 + 5 + 6 51 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following will produce oxygen and hydrogen during its electrolysis using platinum electrode? Dilute sodium chloride solution Concentrated hydrochloric acid Aqueous copper (ll) tetraoxosulphate (IV) Glucose solution 52 / 80 Category: CHEMISTRY PAST QUESTIONS Consider the following equation: Ag+ (aq) + CI-(aq) → Ag+CI- (s) ; ∆H = _65.7 kJmol-1. From the equation, it can be deduced that a solid is formed and heat is evolved the reaction is endothermic and occurs at high temperature direct combination is involved and the reaction is endothermic activation energy is high and a catalyst is required 53 / 80 Category: CHEMISTRY PAST QUESTIONS Elactrostatic force of attraction between sodium ion and halide ion is greatest in NaCI NaBr NaF NaI 54 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following non-metals reacts most readily with metals? Chlorine Sulphur Carbon Nitrogen 55 / 80 Category: CHEMISTRY PAST QUESTIONS What is the value of x in the following equation? Cr2O72- + 14H+ + xe- → 2Cr3+ + 7H2O 12 8 6 1 56 / 80 Category: CHEMISTRY PAST QUESTIONS It can be concluded that gastric juice contains enzymes is acidic has pH value of 7 is a mixture 57 / 80 Category: CHEMISTRY PAST QUESTIONS The liquid product of the destructive distillation of coal is kerosene ethanol ammoniacal liquor paraffin oil 58 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following occurs when a solution of CuSO4 is electrolysed using copper electrodes? The blue colour of the solution fades gradually Both electrodes gain electrons The anode increases in mass The cathode becomes coated with copper 59 / 80 Category: CHEMISTRY PAST QUESTIONS Electrovalent compounds are characterized by solubility in ethanol high molar mass high melting point strong oxidizing ability 60 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following will displace copper from a solution of copper (ll) salt? Magnesium Aluminium ions Zinc ions Silver 61 / 80 Category: CHEMISTRY PAST QUESTIONS What is the shape of a molecule of CCI4? Pyramidal Tetrahedral Linear Trigonal planar 62 / 80 Category: CHEMISTRY PAST QUESTIONS The type of chemical bond that exists between potassium and oxygen in potassium oxide is dative metallic ionic covalent 63 / 80 Category: CHEMISTRY PAST QUESTIONS Helium is preferred to hydrogen in filling balloons because hydrogen is a component of water is inflammable exhibits isotopy is diatomic 64 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following features of a human skeleton can be determined by carbon-dating? Mass Age Race Height 65 / 80 Category: CHEMISTRY PAST QUESTIONS The gas evolved when dilute tetraoxosulphate (VI) acid reacts with sodium hydrogen trioxocarbonate (IV) is sulphur (VI) oxide carbon (IV) oxide hydrogen oxygen 66 / 80 Category: CHEMISTRY PAST QUESTIONS Given that the order of reactivity of four metals is P>Q>R>S, which of the following reactions is feasible? S + P+ → P + S + Q + S+ → S + Q+ R + P+ → P + R+ S + Q+ → Q + S+ 67 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following substances decomposes when an electric current is passed through it? Hydrochloric acid Glucose solution Zinc rod Tetrachlormethane 68 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following compounds dissolves in water to form a solution with pH below 7? Potassium hydroxide Ammonium chloride Sodium tetraoxosulphate (VI) Sodium trioxocarbonate (IV) 69 / 80 Category: CHEMISTRY PAST QUESTIONS The crystal layers in graphite are held together by electrostatic forces hydrogen bonds covalent bonds van der Waals' forces 70 / 80 Category: CHEMISTRY PAST QUESTIONS A concentrated solution containing H+, Cu2+,OH- and CI- was electrolysed using platiunm electrodes which of the ions will be discharged at the cathods? OH- Cu2+ H+ CI- 71 / 80 Category: CHEMISTRY PAST QUESTIONS If an element with high electron affinity combines with another element with low ionization energy the bond formed will be mainly metallic ionic covalent dative 72 / 80 Category: CHEMISTRY PAST QUESTIONS Calcium atom ionizes by gaining two electrons losing two electrons sharing two electrons gaining two protons 73 / 80 Category: CHEMISTRY PAST QUESTIONS P Total = F1 + P2 + P 3 + .........Pn' where P Total is the pressure of a mixture of gasses. The equation above is an expression of Graham's law Boyle's law Gay-Lussac's Law Dalton's law 74 / 80 Category: CHEMISTRY PAST QUESTIONS Chlorine atom forms CI by Sharing one electron Donating lone pair of electrons Gaining one electron Losing one electron 75 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following would dissolve in warm dilute H2SO4 without effervescence, to give a blue solution? Copper turnings Copper (ll) oxide Copper (ll) trioxocarbonate (IV) Copper alloy 76 / 80 Category: CHEMISTRY PAST QUESTIONS Pipe-borne water is usually chlorinated in order to kill harmful bacteria in the water improve the teste of the water coagulate sediments in the water remove the hardness in the water clear 77 / 80 Category: CHEMISTRY PAST QUESTIONS Consider the reaction represented by the following equation: H2(g) + 12(g) → 2HI(g). The number of effective collisions of molecules of the reactants decreases as the temperature is raised the volume of the system is increased the pressure increased a catalysty is intoduced into the system 78 / 80 Category: CHEMISTRY PAST QUESTIONS The presence of unpaired electrons in an atom of a transition metal gives rise to shiny appearance paramagnetism ductility nalleability 79 / 80 Category: CHEMISTRY PAST QUESTIONS How many electrons are removed from Cr2- when it is oxidized to CrO42-? 2 4 0 8 80 / 80 Category: CHEMISTRY PAST QUESTIONS Which of the following compounds dissolves in water to give an alkaline solution? Ammonium chloride Potassium oxide Sodium chloride Sulphur (IV) oxide Your score is 0% Restart quiz Practice also: SS 3 BIOLOGY PAST QUESTIONS (WAEC/NECO) SS 3 AGRIC SCIENCE PAST QUESTIONS (WAEC/NECO) SS 3 COMPUTER STUDIES PAST QUESTIONS (WAEC/NECO) SS 3 COMMERCE PAST QUESTIONS (WAEC/NECO) SS 3 DATA PROCESSING PAST QUESTIONS (WAEC/NECO)