mitrobeWelcome to mitrobenetwork, In today’s exam question sections for University school students, you will get yourself acquainted with free Chemistry Past Questions | JAMB, WAEC, NECO and Post UTME Past Questions.
1. When a solid substance disappears completely as a gas on heating, the substance is saki to have undergone
A. evaporation B. distillation C. crystallizat!on D. sublimation
2. A chemical reaction is always associated with A. an increase in the composition of one of the
substances.
B. a change in the volume of the reactants
C. a change in the nature of the reactants
D. the formation of new substances
3. If a solution contains 4.9g of tetraoxosulphate(VI) acid, calculate the amount of copper (II) oxide that will react with it.
A. 0.8g B. 4.Og C. 40.Og D. 80.Og [Cu=C4,O=16,S=32,H1]
4. What volume of gas is evolved at s.t.p. if 2g cf calcium trioxocarbonate (IV) is added to a solution of hydrochloric acid?
A. 112cm3 B. 224cm3 C. 448cm3 D. 2240cm3[Ca = 40, C = 12,0 = 16, CI = 35.5, H = 1,
Molar volume of a gas at s.t.p. = 22.4dm3]
5. According to Charles’ law, the volume of a gas becomes zero at A. 0°C B. —100°C C. —273°C D. —373°C
6. It is difficult to achieve an orderly arrangement of the molecules of a gas because they A. have no definite shape B. have little force of attraction between them C.. can collide with one another in the container D. are too small in size.
7. A given volume of methane diffuses in 20s. How long will it take the same volume of sulphur (IV)oxide to diffuse under the same conditions? A. 5s B. 20s C.40s D.60s [C = 12, H = 1, S = 32, 0 = 16]
8. An electron can be added to a halogen atom to form a halide ion with A. 2 valence electrons B. 3 valence electrons
C. 7 valence electrons D. 8 vler.ce electrons
9. The shape of the s-orbital is A. sphericaI B. elliptical C. spiral D.circular
Ra —* Rn + a — particle
10.What is the vaue of x in the nuclear reaction above? A. 220 B. 222 C. 226 D. 227
11. The property of chlorine which causes hydrogenchridë to be more ionic than the chlorine molecule
‘A. its electrovalency B. electron affinity C. electropositivity D. electronegativity
12. Chlorine consisting of two isotopes of mass numbers 35 and 37 in the ratio 3:1 has an atomic mass of 35.5.
13.Calculate the relative abundance of the isotope of mass number 37.A. 20 B. 25 C. 60 D. 75
14. Which of the following mixtures of gases is likely to burn in flame? A. neon and hydrogen B. nitrogen and helium
C. helium and neon D. neon and nitrogen
15. Hardness of.water is caused by the presence of the ions ofA. magnesium and silver B. calcium and magnesium C. sodium and potassium D calcium and sodium
16. Pollution of underground water by metal ions is very likely in a soil that has high
A. acidity B. alkalinity C. chloride content D. nitrate content
17. A carcinogenic substance is A. asbestos dust B. sawdust C. nitrogen (ii) oxide D. carbon (II) oxide
18. The solubility in mel dm-3 of 20g of CuSO4 dissolved in bOg of water at 180°C is
A. 0.13 B. 0.25 C. 1.25 0. 2.00 [Cu64,S32,016]
19. Calcium tetraoxosulphate (VI) dissolves in watcr only sparingly to form a
A. solution B. suspension C. precipitate
D. colloid
20. Which of these compounds is a nc.rmal salt?
A. NaHS B. NaHSO C. NaHCO3 D.Na,C03
21. What volume of 0.5 mol dm-3 H SO4 will exactly neutralize 20cm3 of 0.1 mol dm3 f\JaOH solution? A. 2.0 cm3 B. 5.0 cm3 C. 6.8 cm3 0. 8.3 cm3
22. The oxidation state of chlorine in HCIO4 is A. —5 B. —1 C. +1 D. +7
ZnO(S) + °°)g) Zn)5) + CC2)2)
23. In the reaction above, zinc has been A. decomposed B. displaced C. oxidized D. reduced
24. Which of the following acts as both a reducing and an oxidizing agent? A. H2 B. SO2 C. H2S D. CO2
25. In the electrolysis of brine, the anode is A. platinum B. copper C. zinc D. carbon
26. The mass of silver deposited when a current of iDA is passed through a solution of silver salt for 4830s is
A. 108.Og B. 54.Og C. 27.Og D. 13.5g [Ag = 108, F = 96500 C mol-1]
27. 2 Co +0 —>2Co (g) 2(g) 2(g) Given that AH [CO] is — 110.4 kJmol1 and AH [CC2] is — 393.0 kJmoM, the energy change for the reaction above is
A. —503.7 kJ B. —282.6 kJ C. +282.6 kJ D. +503.7 kJ
28. Which of the following hydrogen halides has the highest entropy value?
A. HF B. HCI C. HBr D. HI
29. N2O4)g). ‘2NO2(2) In the endothermic reaction above, more product formation will be favoured by A. a constant volume B. an increase in pressure C. a decrease in pressure- D. a decrease in volume
30. Which of the following shows little or no net reaction when the volume of the system is decreased?
A. H2)2) + ‘2)g) ‘2Hl)9)
B. 2NO2)2) … N2O4)Q)
C. PCI5)2) PCI3)g) + C12)Q)
0. 2O3)) 302(g)
31. The allotrope of carbon used in the decolourization of sugar is A. graphite B. soot C. charcoal D. Iampblack
32. Which of the following gases can be collected by the method of downward delivery? A. chlorine B. oxygen C. ammonia D. hydrogen
33. vviieii Sledni pdSeu o eu-hu arbon, the substances produced are A. hydrogen a’d trioxocarbonate (IV) acid
B. hydrogen, oxygen and carbon (IV) oxide C. hydrogen and carbon (II) oxide
D. hydrogen and carbon (IV) oxide
34. Sulphur (IV) oxide bleaches by A. reductkn B. oxidation C. hydration D. adsorption
35. Carbon is tetravalent because A. the electrons in both the 2s aftd 2p orbitas are equivalent
23. B. the electrons in all the orbitals of carbon are equivalent C. the 2s and 2p atomic orbitals hybridize
D. all the atomic orbitals of carbon hybridize
36. Aluminium hydroxide is used in the dyeing industry as a A. salt B. dye C. mordant D. dispersant
37. Alloys are best prepared by A. electroplating B. arc-welding C. reducing a mixture of their metallic oxides
D. cooling a molten mixture of the metals.
38. Transition metals possess variable oxidation states because they have A. electrons in the d orbitals
B. electrons in the s orbitals C. a variable number of electrons in the p orbitals D. partially filled p orbitals
39. Sodium metal is always kept under oil because it A. readily reacts with water B. is reduced by atmospheric nitrogen C. reacts vigorously on exposure to air D. reacts with oxygen and carbon(lV)oxide
40. Oxyacetylene flame is used for iron-welding because it A. makes the iron metal solidify very quickly
B. combines with oxygen to give a pop sound C. evolves a lot of heat when burnt D. dissociates to produce carbon (IV) oxide and oxygen
41. The alkyl group can be represented by the general formula A. CH21 B. CH2 C. CH22 D. CH22
42. An isomer of CH1 is A. butane . 2 — methylbutane C: 2 — methylpropane D. 2 — ethylbutane
43. A characteristic of the alkane family is A. addition reaction B. elimination reaction C. substitution reaction D. neutralization reaction.
44. Which of these reagents can confirm the presence of a triple bond? A. Bromine water B. Acidified KMnO4
C. Copper (I) chloride D. Bromine gas
45 Vulcanization involves the removal of A. a monomer B. the single bond
C. the double bond D. a polymer.
SECTION A – OBJECTIVES [50MARKS] Instructions: Answer all questions
1. Chemistry can be applied in the following fields EXCEPT A. Agriculture B. Oil and gas C. Politics D. Metallurgy
2. Separation of mixtures of solids with various sizes can be done A. Magnetic separation B. Coarsing C. Sublimation D. Sieving
3. Which of the following is an example of a chemical change? A. Dissolution of salt in water B. Rusting of iron C. Melting of ice D. Separating of mixture by distillation
4. These are basic particles from which matter could be made EXCEPT A. Salt B. Atoms C. Ions D. Molecules
A molecule of neon is A. Diatomic B. Ionic C. Triatomic D. Minoatomic
5.Which of these requires crystallization most? A. Drug making B. Cement making C. Paint making D. Perfume making
6. Which one is the odd-one out? A. Air B. Urine C. Brass D. Sand
7. Chemical hypothesis is different from chemical law that A. Hypothesis is not reasonable explanation to observation made while law is reasonable B. Hypothesis is a reasonable explanation to observations while law is a statement from a scientist C. Hypothesis is a reasonable explanation to observations while law is a statement which confirms the hypothesis after extensive tests D. None of the above
8. Separating funnel is used for separating a mixture of A. Liquids with different boiling points B. Liquids with sediment C. Liquids with different colour D. Liquids that are immiscible
9.The simplest unit of water that retains its properties is called? A. An atom B. An element C. An hydroxide D. A molecule
10. Of the basic particles that make up an atom, the one with the smallest mass is A. A proton B. A neutron C. An ∝-particle D. An electron
11. The atomic mass of an element is mostly due to the mass of A. Electrons and protons B. Electrons and neutrons C. Protons and neutrons D. Positions and neutrons
12. One of the following is NOT a branch of chemistry A. Analytical chemistry B. Medicinal chemistry C. Organic Chemistry D. Hybrid chemistry
13. One of these professions has no need for chemistry A. Mining B. Engineering C. Philosophy D. Geology
14. How many molecules are there in 1 mole of chlorine molecules? A. 35.5 molecules B. 6.02 x 10-23 molecules C. 17.0 molecules D. 6.02 x 23 molecules
15. A heterogeneous mixture can be defined as any mixture A. Whose compositions combine to produce a uniform substance B. Whose compositions combine to produce a non-uniform substance C. Formed by solids and liquids D. Of a solute and a solvent
16. Atomicity of Ozone is A. 1 B. 2 C. 3 D. 4 The relative molecular mass of Lead (ii) trioxonitrate (v) is? (Pb = 207,
N = 14, O = 16) A. 170 B. 222 C. 232 D. 132
17. The percentage of oxygen in sulphur(iv) oxide is (S = 32, O=16) A. 5% B. 50% C. 500% D. 25%
18.The empirical formula of C6¬H6 is A. CH B. C3H3 C. C6H6 D. 3CH
19. Which of the following techniques can be used to obtained ethanol from a mixture of ethanol and water? A. Boiling B. Chromatography C. Crystallization D. Distillation
20. What is the relationship between empirical formula and molecular formula? A. Empirical formula = Molecular formula B. Empirical formula = n x molecular formula (n=1,2,3…) C. Molecular formula = n x Empirical formula (n = 1, 2,3…) D. Molecular formula x Empirical formula = 1
21. Based on the IUPAC way of representing symbols, the symbol for Iron is A. He B. Ir C. Ion D. Fe
Calculate the percentage by mass of Lead in 1 mole of Pb (NO3)2
(Pb = 207; N = 14, 0 = 16) A. 76.9% b. 62.5% C. 77.5% D. 87.3%
22. How many moles of magnesium atoms are present in 0.80g of magnesium? (Mg = 24) A. 0.003mole B. 0.30mole C. 0.33mole D. 0.03mole
23. Modern standard element with which chemists define relative atomic mass is A. 12C B. 13C C. 3H D. 14C
24. Which of the following are mixtures? (i) Petroleum (ii) Rubber latx (iii) Vulcanizers solution (iv) carbon (ii) sulphur A. i, ii and iii B. i, ii and iv C. i and iii only D. i and iv
25. Which of the following substances is NOT a homogenous mixture? A. Filtered seawater B. Soft drink c. Flood water D. writing ink
26. Fractional crystallization is a method of separating A. Crude oil B. Liquid-liquid mixture C. coal D. solids of different solubilities in a liquid
27. There are three main states of matter; liquid, solid, and gas. All have different properties. Which statement describes the physical state of a solid but not a liquid or gas? A. It has its own shape B. It does not have its own shape C. It takes the shape of its container D. It changes shape with temperature
28. Which of the following is a property of both liquids and gases, but not solids? A. Can flow B. Can be compressed C. Has a definite shape D. Has a definite texture
29. Chemical symbol represents A. Chemical formula B. Molecular formula C. Structural formula D. Atomic formula
30.A modern model of an atom show that electrons are present outside the nucleus in region of highest A. Probability B. Velocity C. Speed D. Energy level
31. Smaller particles in an atom are called A. Atomic particles B. Subatomic particles C. Smaller particles D. Neutral particles
32. At room temperature, helium does Not have a definite shape or volume. Which state is it in? A. Gas B. Solid C. Water D. Liquid
33. Which property determines whether one substance will sink or float in another substance? A. Texture B. Density C. Volume D. Temperature
34. The water supply system in your town is contamin with salt water. Drinking water can be obtained from the contaminated water by A. Filtration B. Evaporation C. Crystallization D. Distillation
35. Which of the following methods would you recommend to recover Iron pieces from a garbage dump containing dry leaves, papers and broken glass? A. Burning of leaves and paper B. Filtration C. Hand picking of iron pieces D. Magnetic separation
36. The criteria to verify the purity of a solid substance are I. Boiling point II. Melting paint III. Density IV. Refractive Index A. I, II B. II, III C. I, II, III D. I, IV
37. Valency is the combining power of an element. The valency of Nitrogen is A. 1 B.2 C.3 D. 2 or 3
38. What is the mass in grammes of 0.50mole of oxygen atoms? (O= 16)
A. 0.50g B. 2.0g C. 5.0g D. 8.0g
39. The mass spectrometer is used to measure A. The number of protons in the nucleus of atom B. The number of electrons in an atom C. The relative molecular mass of an atom D. Quantity of mass
40.A molecule of neon is A. N B. N2 C. Ne D. Nez
41. One mole of oxygen atoms A. Has a molar mass of 32g B. Has 6.02 x 1023 molecules C. Can be represented as O2 D. Contains Avogadro’s number of atoms
42. The constituents of a leaf pigment can be separated by A. Chromatography B. Filtration C. Fractional crystallization D. Fractional distillation
43. An element X with relative atomic mass 16.2 contains two isotopes (_8^16)X with relative abundance of 90% and (_8^m)X with relative abundance of 10%. The value of m is A. 14 B. 12 C. 18 D.16
44. What is the percentage of mass of sodium in sodium hydroxide (Na = 23, O = 16, H =1) A. 40.4% B. 42.5% C. 57.2% D. 73.0%
45. Neutral atoms of neon with atomic number 10 have the same number of electrons as A. 02- B. Ca2+ C. K+ D. S2-
The modern way of representing symbols was developed in 1818 by
A. Einstein B. Berzelius C. Dalton D. Rutherford
46.In countries where temperatures are most times far below zero, why is common salt sprinkled on the icy-roads? A. To remove impurities B. To lower the melting point of the ice
SECTION B – THEORY
Instruction: This section is divided into two parts. Attempt only ONE question in part I and any THREE (3) questions in Part II
PART I [40MARKS] 1. Using a neat diagram, explain how a mixture of two immiscible liquids of your choice can be separated.
2a. Define the terms (i) mixture (ii)compound. Give three differences between them
b. Classify the following substances as an element, a mixture or a compound (i) Limestone (ii) Diamond (iii) Sand (iv) Soil (v) Urine (vi) Bronze (vii) Sugar (viii) Gold (ix) Clay (x) Urea (xi) Antimony (xii) Soap (xiii) Milk (xiv) Air (xv) Neon (xvi) Iron
c. Why is sodium chloride solution regarded as a mixture?
d. How would you separate the components of the following mixtures?
(i) A mixture of sodium chloride and ammonium chloride (ii) A mixture of Iron dust and zinc dust (iii)A mixture of water and sugar
(iv) A mixture of two solids which have widely different solubilitus in water (v) A pure solid from a concentrated solution of its salt.
PART II [ 60 MARKS]
3. State Dalton’s atomic theory and its corresponding modification
4a. How is a Homogenous mixture different from a Heterogeneous mixture?
b. Classify each of the following changes as either a physical change or a chemical change
(i) The addition of water to quicklime
(ii) The melting of candle ware
(iii) The change in colour of zinc oxide from white to yellow when
Heated
(iv) The hardening of cement by the absorption of carbon(iv) oxide
(v) The addition of a base to an acid to form salt and water only
5a. Define the relative atomic mass of an element
b. Calculate the relative molecular mass of;
i. Slaked lime, Ca(OH)2
ii. Sodium trioxonitrate(v), Na¬NO¬3
iii. Hydrated copper(ii) tetraoxosulphate(vi), CuSO4 – 5H2O
c. What do you understand by the atomicity of an element?
(Ca = 40; O = 16; H=1; Na = 23; N = 28; S = 32; Cu = 64)
6. Find the empirical formula of a compound which on analysis yields the following as the reacting masses. Carbon = 2.0g, hydrogen = 0.34g, Oxygen = 2.67g. from your result, find the molecular formula of the compound, if its relative molecular mass is 60.
7a. Define the following
(i) Mole (ii) Molecule (iii) Iron (iv) atom
b. How many moles are there in 20g of CaCO3?
c. Calculate the percentage by mass of nitrogen in trioxonitrate(v) acid
SECTION A – OBJECTIVES [50MARKS] Instructions: Answer all questions
1. The atoms of four elements are represented as 20Q, 16R, 10S and 8T. which of the elements would be unreactive A. Q B. R C. S D. T
2. The type of chemical bond that exists between potassium and oxygen in potassium oxide is A. Ionic B. Metallic C. Covalent D. Dative
3. Chlorine atom forms Cl- by A. Losing one electron B. Sharing one electron C. Donating one pair of electrons D. Gaining one electron
4. An element Z has a combining power of 3. Which of the following formulae is correct of its compound A. ZSO3 B. Z3Cl2 C. Z2O3 D. ZS3
5. The gas evolved when dilute tetraoxosulphate(iv) acid reacts with sodium hydrogentrioxocarbonate(iv) is A. Hydrogen B. OxygenC. Carbon(iv)oxide D. Sulphur(vi)oxide
6. If a solution has a pH of 2, it can be concluded that it A. Is a weak electrolyte B. has hydrogen concentration of 0.2moldm-3 C. Is twice as acidic as a solution of pH, D. Will produce effervescence with magnesium ribbon
7. Chemical equilibrium is attained when A. Reactants in the system are used up B. Concentrations of the products are greater than those of the reactants C. Concentrations of the reactants and products remain constant D. reactants stop forming the products
8.An iron nail placed in a solution of copper(ii)tetraoxosulphate(vi) is soon covered with a deposit of copper. Which of the following equations represents the reaction?
A. Fe2+(aq) + Cu(s) Fe3+(aq)
B. Fe2+(aq) + Cu(s) Fe(s) + Cu2+(aq)
C. Fe(s) + Cu2+(aq) Fe2+(aq) + Cu2+(aq)
D. Fe(s) + Cu2+(aq) Fe2+(aq)
9.Which of the following non-metals reacts most readily with metals? A. Nitrogen B. Chlorine C. Sulphur D. Carbon
A radioactive substance is best stored A. Under paraffin oil B. Under ultravidet light C. In a cool, dark cupboard D. In a box lined with lead
10.In the electrolytic extraction of aluminum from puried alumina; molten cryolite is added in order to A. lower the melting point of the alumina B. Prevent the aerial oxidation of the molten aluminum C. Lower the activation energy of the reaction D. Form a protective crust on top of the electrolyte
11. When iron rusts, it undergoes A. Deliquescence B. Chemical decomposition C. Hydrolysis D. Redox reaction
Which of the following involves the decomposition of a sugar by enzymic action? A. Esterification B. Fermentation C. Dehydration D. Polymerization
12. If a reaction is said to be exothermic, which of the following statements is a correct deduction from the information? A. The reaction vessel gets hotter as the reaction proceeds B. ∆H for the reaction is positive C. The rate of the reaction increases with time D. The activation energy of the reaction is high
13. A dye s suspected to have contaminated a lollipop. Which of the following is the best method by which the contaminant may be isolated?
A. Fractional distillation B. Recrystallization C. Filtration D. Paper Chromatography
14. Which of the following accounts for the difference in the mode of conduction of electricity by metals and aqueous salt solutions?
A. Electrons are present in metals but not in salt solutions B. Metals are conducted while salts are electrolytes C. Electricity is carried by mobile electrons in metals but by ions in aqueous salt solution D. Salts ionize in aqueous solutions while metals do not.
15. A positive brown ring test indicates the presence of A. NO-3¬ B. Fe3+
C. 〖SO〗_3^(2-) D. Cu+
16. The following statements about graphite are correct EXCEPT that it A. Is used as a lubricant B. Has a network structure C. Contains mobile free electrons D. Is a good conductor
17. Which of the following hydrocarbons is unsaturated? A. Ethane B. Benzene C. Propane D. Z-methylbutane
18. Which of the following is an alloy of mercury? A. Stainless steel B. Soft solder C. Coinage bronze D. Amalgam
19.Metals which react with steam only when they are red-hot include
A. Copper B. Sodium C. Calcium D. Iron
20.An arrangement of two different metals in aqueous solutions of their salts to produce an electric current is known as A. Electrochemical cell B. Activity series C. Thermocouple D. Volmeter
21. Which of the following exhibits resonance? A. Benzene B. Butane
C. Pentene D. Octane
22. Which of the following metals will be the most suitable for use where lightness and resistance to corrosion are of important? A. Lead B. Copper C. Iron D. Aluminum
23.What is the most probable group of an element which is a soft, silvery-white solid and reacts violently with water? A. Group O B. Group 1 C. Group 4 D. Group 6
24. Which of the following ions will migrate to the cathode during electrolysis? A. Zinc ions B. Chloride ions C. Suphide ions D. Tetraoxosulphate(vi)ions
25. Which of the following radioactive decays involve an ∝-β emission?
A. (_92^238)U →(_90^234)Th +(_2^4)He B. (_80^238)Hg →(_81^238)Tl C. (_50^199)Sn →(_50^199)Sn
D. (_1^2)H+ (_1^2)H →(_1^3)H + (_1^1)H
25. The following oxides react with both acids and bases to form salts except A. Zinc oxide B. Lead (ii) oxide C. Aluminium oxide D. Carbon(iv)oxide
26. Which of the following metals is NOT extracted by electrolysis? A. Iron B. Sodium C. Calcium D. Magnesium
Which of the following is an ore of aluminum? A. Haematite B. Magnetite C. Siderite D. Bauxite
27. Which of the following statements is/are correct about metals? They I. Are good conductors of electricity II. Have mobile electrons III are reducing agent IV. Form acidic oxides A. I and II only B. I, II and III only C. I, II, III and IV D. None of the above.
28.The main type of reaction that occurs in the blast furnace during the extraction of Iron is A. reduction reaction B. Decomposition C. Exothermic reaction D. Combustion
29. Which of the following compounds can be represented by the molecule formula C2H6O A. Propanal B. Ethanol C. Methanoic acid D. Glucose
30. The following compounds are hydrocarbons EXCEPT
A. Methylpropanoate B. Z-methylbutane C. Benzene D. Cyclohexane
31. When alkynes are hydrogenated completely, they produce compounds with the general molecular formula A. CnHn B. CnH2n+2 C. CnH2n D. CnH2n-2
32. Which of the following alloys does not contain copper? I. Brass II. Bronze III. Steel A. I only B. II only C. III only D. II and III only
33. The major product in the solvay process is A. NaOH B. Na2CO3 C. NH3 D. H2SO4
100g of radioactive mass has a half-life of 5 days. Calculate the mass decayed off after 15 days. A. 25g B. 50g C. 12.5g D. 6.25g
34. A solution of sodium trioxocarbonate(iv) contains 10.6g in 250cm3 of solution. Calculate the concentration of the solution. A. 0.4moldm-3
B. 1.0moldm-3 C. 10.6moldm-3 D. 25.0moldm-3
35. The rate of chemical reaction of solids are not affected by A. Catalyst B. pressure C. Particle size D. Temperature
The energy change that accompanies the addition of an electron to an isolated gaseous atom is A. Bond energy B. electronegativity C. electron affinity D. Ionization energy
36. Which of the following metals could be used as sacrificial anode for preventing the corrosion of iron? A. Copper B. Lead C. Magnesium D. Silver
37. What mass of copper would be formed when a current of 10.0A is passed through a solution of CuSO4 for 1hour? A. 5.9g B.11.8g C. 23.7g D. 47.3g¬
38. The volume occupied by 0.4¬¬g of hydrogen gas at S.t.p is A.2.2dm3 B. 4.48dm3 C. 22.4dm3 D. 44.8dm3
39. The oxidation number of Fe in [Fe(CN)6]3- is A. +3 B. +2 C. -2 D. -3
40. Which of the following substances is mainly responsible for the depletion of the ozone layer? A. Oxygen B. Chlorofluorocarbon C. Carbon(ii)oxide D. Nitrogen(ii)oxide
41. Which of the following reactions is common to all hydrocarbons?
A. Combustion B. Addition C. Polymerization D. Condensation
42. A hydrocarbon compound contains 92.3% carbon. Determine its empirical formula A. CH B. CH2 C. CH3 D. C2H3
43. Reduction is the process of A. Loss of electron B. Loss of hydrogen
C. loss of oxygen D. Addition of electronegative elements
SECTION B – THEORY
Instruction: This section is divided into two parts, answer only two questions from each part.
PART I [ 50 MARKS]
1.(a) What are nucleons?
(b) State Graham’s law of diffusion
(c) Explain briefly why aluminum does not corrode easily
(d) State THREE examples of periodic properties and their variations in the periodic table of elements
(e) State TWO reasons why real gases deviate from ideal gas behave iour
(f) List THREE uses of fractional distillation in industry
(g) What factors determine the selective discharge of ions at the electrodes during electrolysis?
(h) Consider the reaction represented by the following equation
Na2CO3(aq) + MgCl2 2NaCl(aq) + MgCO3(aq)¬
2a. Consider the following atoms
(_T^(R ))X; (_T^S) X
i. State the phenomenon exhibited by the two atoms
ii. What is the difference between the atoms?
iii. Give two examples of elements that exhibit the phenomenon stated in 2(a)(i)
iv If T is 17, write the electron configuration of the element
b(i) State two differences between metals and non-metals with respect to their: I. Physical properties (ii) Chemical properties
b (ii) Give one example of each of the following compounds
An amphoteric oxide
A hydride which evolves hydrogen when reacted with water;
A trioxocarbonate(iv) salt which is readily decomposed on heating
A chloride salt which is readily hydrolyzed in water
c(i) State THREE characteristic properties of transition metals
(ii) Write the electro configuration of 30Zn
(iii) Explain briefly why zinc is not considered as a typical transition element
3(ai) State Graham’s Law of diffusion
(aii) If 100cm3 of oxygen diffused in 4seconds and 50cm3 of gas Y diffused in 3 seconds, Calculate the relative molecular mass of gas Y
X(g)+2Y(g XY2(g)¬ ∆H = -52KJmol-1
i) State what happens to the yield of XY2 when the temperature is increased
(ii) Explain the effect of decrease in pressure on the equilibrium position
(iii) State the effect of a catalyst on the
Position of equilibrium
Activation energy
c.(i) State two differences between the solubilities of solids and gases in liquids
c.(ii) Name the physical properties used in choosing separation techniques for the following mixtures I. Kerosene and Petrol II. Calcium trioxocarbonate (iv) and potassium chloride III. Ammonium chloride and sodium chloride
d(i) State a method of preparing each of the following salts;
Sodium Chloride
Lead (II) Trioxocarbonate (iv)
Iron (ii) Chloride
Copy and complete the table below
Acid Basicity
H3PO4
CH3COOH
HNO3
D(i) State the difference between analydrous and hydrated salts
PART II [50 MARKS]
4a. What is the main source of aluminium in nature?
b. Using a diagram and equations, explain how pure aluminium is extracted from the above source
c. The common radioactive isotope of radium – 226 has a half-life of 1620 years. Calculate:
i. The first order rate constant for the decay of radium – 226
ii. The fraction of a sample which remains after 100years.
5a. Using diagrams and equations, explain how iron is extracted from its ores.
b. What is the chemical nature of iron rust? How would you attempt to determine by a series of chemical reactions that iron rust contains iron?
c. Write short notes on the following (i) cast iron (ii) wrong iron (iii) pig iron (iv) steel
3a(i) What is a solution?
(ii) Why is water regarded as a universal solvent?
b. Ethane burns completely in oxygen; what is the amount in moles of carbon (iv) oxide that will be produced when 6.0g of ethane are completely burnt in oxygen?
c. A solution of trioxonitrate(v) acid contained 0.67g in 100cm3 31cm3 of this solution neutralized 25cm3 of a sodium trioxocarbonate(iv) solution. Calculate the concentration of the trioxocarbonate (iv) solution
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