Second Term Examination Chemistry SS 3 Second Term

MOCK EXAMINATION

Examination malpractices may lead to a repeat of the subject or suspensions don’t be involved.

SUBJECT: CHEMISTRY TIME ALLOWED: 2HRS. 30MINS CLASS: S.S 3

1.If the relative molecular mass of an element is not a whole number, it can be deduced that the element is

a. naturally radioactive b. abundant in nature c. a transition metal d. an isotopic mixture

1. Which of the following decreases when a given mass of gas is compressed to half its initial volume? A. average intermolecular distances b. frequency of collisions

c. number of molecules present d. atomic radius of each particle

1. Calculate the mass of chlorine gas which occupies a volume of 1.12dm³ at s.t.p.

(Cl=35.5,1 mole of gas occupies 22.4dm³ at s.t.p. a.1.80g b.3.55g c.7.10g d.15.50g

1. Determine the mass of sulphur(iv) oxide obtained when 91.0g of oxygen reacts completely with sulphur according to the following equations S_(s)+O₂——-SO₂(g).(S=32,O=16)

a.123g b.139g c.155g d.182g

1. Which of the following elements form an ionic chloride? A. magnesium b .carbon c. phosphorus d. Hydrogen

2. A sample of orange juice is suspected to have been contaminated with a yellow dye. Which of the following methods can be used to detect the dye?

Decantation b) chromatography (c) distillation (d) filtration (e) evaporation

1. The bond between two iodine molecules is (a).co-ordinate bond (b) electrovalent bond (c).ionic bond (d)van der waal’s forces

2. Bonds between a highly electronegative atom and a hydrogen from another molecule is called (a).hydrogen bond (b).covalent bond (c).intermolecular forces (d).ligand.

9.The nitride ion is N^-3.What is the formula of the nitride of an alkali metal X.

a.X₃N₅ B.XN₃ C.X₂N₃ d.X₃N

10.What type of chemical bonding is involved in the formation of NH₄⁺ from a molecule of ammonia and a proton. a. Hydrogen bonding b. co-ordinate covalent bonding c. electrovalent bonding d. covalent bonding

1. Which of the following properties of elements decreases generally across a period in the periodic table? (a) electronegativity (b) electron affinity (c) atomic radius (d) ionization energy.

2. The heat of combustion of carbon(ii)oxide is -60KJ.Calculate the heat evolved when 14g of CO are burnt.(C=12, O=16). a.300KJ b.200KJ C.30KJ d.15KJ

3. One of the following will not affect a chemical system at equilibrium

a. Temperature b. Catalyst c. Pressure d. Concentration

1. The product of an endothermic reaction are

a. higher in enthalpy than the reactant b. lower in enthalpy than the reactant

c .the same in enthalpy as the reactant d. the change in enthalpy is less than zero

1. Which of the following metals will react with cold water to produce hydrogen gas?

a. calcium b. aluminium c. copper d .magnessium

1. Which component of air is removed when air is bubbled through a solution of alkaline pyrogallol? a.carbon (iv)oxide b.Nitrogen c.Oxygen d.Helium

17.Oygen is obtained from liquid air by a. Fermentation b. Fractional distillation

c. Filtration d. Sublimation

1. A system is in equilibrium when a. ∆G is positive b.∆ G is negative c. ∆G is zero d. ∆G is constant.

18.Halogens are a. strong reducing agents b. strong oxidizing agents

c. strong actions d. strong donors of electrons

1. Chlorine is best collected by a. upward displacement of air b. downward displacement of air c. over water d .over mercury

2. Which of the oxides of nitrogen is a neutral oxide? a.N₂O₄ b.NO₂ C.N₂O₅ d.NO

21.Plastic sulphur is a. A crystalline allotrope of sulphur b. A super cooled form of sulphur

c. A form of sulphur rings packed together

d. Forms monoclinic sulphur when left

22.What will happen if more heat is

applied to the following system at equilibrium? X₂+3Y₂¬˾2XY_3(g) ΔH=xkjmol^-1

a. the yield of XY₃ will increase b. more of XY₃ will decompose c. more of X₂ will react

D. the forward reaction will go into completion.

23.Effervescence occurs when water comes in contact with a.calcium b. copper c. sulphur d. lead

1. 1. The gas that can be best collected by downward displacement of air (a) chlorine (b) carbon(iv)oxide (c) sulphur (iv)oxide (d) ammonia

Consider the reaction : CO(g)+H₂O˾¬CO₂(g)+H₂(g)

ΔH=-41KJmol^-1

25.Which of the following conditions has no effect on the equilibrium mixture?

a. pressure applied on the system b. temperature of the system c. removal of one of the reactants d. removal of the products as they are formed.

26.If copper has an oxidation state of +2 in a complex ion represented as (Cu(X)₄)⁺²

What is the electrical charge of X? a.-4 b.-2 c.0 d.-2

27.Which of the following equation represents direct combination?

a. Fe³⁺ _(aq) + e^– —Fe²⁺ b. H⁺_(aq) +OH^–—-H₂O_(aq) c. Zn +Cl₂—–ZnCl₂(s)

d. Ag_(aq) +Cl^–—–AgCl_(s)

1. The following are characteristics of colloids except

a. tyndal effect on light beam b. solid phase are removed by dialysis c. colloidal particles are larger than that of suspensions

d. colloidal particles are separated using parchment membranes.

1. 144 g of KCl dissolved in 1dm³ of water at 90°C in the presence of excess crystals of KCl. Calculate the solubility of KCl at this temperature.(K=39,Cl=35.5)

a.0.89moldm^-3 b.1.93moldm^-3 c.1.75 moldm^-3 d.1.5moldm^-3

1. What is the volume occupied by 2 moles of ammonia at S.T.P?

A. 44.8dm^-3 B. 22.4dm^-3 C. 11.2dm^-3 D. 5.6dm^-3

31.Cr₂O^-2₇ + 14H⁺ + xe ^– 2Cr³⁺ + 7H₂O

The number of moles(x) of electrons in the above half cell equation is: (a) 2 (b) 4 (c) 7 (d) 6

1. the volume occupied by 0.4g of hydrogen gas at STP is (H=1.00, molar volume at STP =22.4 dm³)

(a) 2.24 dm³ (b) 4.48dm³ (c) 22.4dm³ (d) 8.96 dm³

1. A measure of degree of disorderliness in a chemical system is known as: (a)enthalpy (b) free energy (c) entropy (d) activation energy

2. H_2(g)+ x_2(g) 2HX_(g) ΔH=positive. In the above reaction,a decrease in temperature will:

(a) decrease the concentration of HX (b) favour the forward reaction

(c) favour the yield HX (d) have no effect on the equilibrium position

1. 3Fe_(s)+4H₂O_(g) Fe_­3O₄+ 4H_2(g) .The equilibrium constant K of the reaction above is represented as: (a) [H₂]⁴/[H₂O]⁴ (b) [Fe]³ [H₂O]⁴ /[Fe₃O₄] [H­₂]⁴ (c)[Fe₃O₄][H₂]⁴/[Fe]³[H₂O]⁴ (d)[H₂]⁴/[H₂]⁴

2. What is the quantity of electricity produced when a current of 0.5 A is passed for 5 hours 45 minutes (F=96500)? (a)0.11F (b)0.22F (c) 0.12F (d) 1.1F

3. The shape of water molecule is a. angular b. tetraheral c. pyramidal d. linear

38.The quantity of petrol obtained from crudeoil can be increased by

redistilling the heavier fractions b. condensing the lighter fractions

polymerizing the lighter fractions d. cracking the heavier

1. If an excess of liquid hydrocarbon is poured into a jar of chlorine and the sealed jar is then exposed for several hours to bright sunlight, all the chlorine gas is consumed. The hydrocarbon is said to have undergone. (a) apoly merization reaction (b) an addition reaction (c) a substitution reaction (d) a reduction reaction

Give the IUPAC name for the structure O

CH₃CH₂C

NH₂

(a) Propanamide (b) Propanamine (c) Amino propane (d) Ammonia Proponoic acid

1. Which of these Homolygnos has the small of fish or fishy odour?

(a) alkanois (b) Aminos (c) Alkanoates (d) Ether

41.A carbon hydrocarbons consists of 92.35% carbon. If its vapour density is 39,determine its molecular formular. a.C₃H₃ b.C₆H₆ c.CH d.C₉H_9.

1. A solutions of sodium trioxocarbonate (iv) contains 10.6g in 250cm³ of solution. Calculate the concentration of the solution. [Na₂CO₃ = 106.0]

A. 0.4mol dm^-3 B. 1.0moldm^-3 C. 10.6moldm^-3 D. 25.0moldm^-3

1. Iron is paramagnetic because a. its orbitals have few unpaired electrons b. its orbitals have only paired electrons c. iron has large number of unpaired electrons d. it is ferromagnetic

2. Zinc is not regarded as a transitional metal even though it is a d-block element because

a. it has no electron in 3 d-block b. it has all 3 d-orbitals completely filled c.it blends with other neighbouring elements d. it does not form complex ion like others.

1. Dehydration of carbohydrate by concentrated H₂SO₄ will give (a) black residue of carbon (b) the components monosaccharides (c) sooth of coal (d) a yellow – brown known as caramel.

2. Which of the following is used for the removal of impurities from bauxite? (a)Na₃AIF₆ (b) NaOH (c) H₂SO₄ (d) CaCO₃

3. Consider the reaction represented by the following equation:

H-C≡C-H ^H2 X ^H2Y; X and Y respectively are

A. ethene and ethane B. ethane and ethane C. ethyne and ethane D. ethane and propene

1. Compound N reacts with sodium metal to produce a gas that gives a “pop” sound with a burning splint. N also reacts with ethanol to give a sweet smelling liquid. Compound N is an

A. alkanol B. alkanoate C. alkane D. alkanoic acid

 

1. The IUPAC name of the compound

CH₃ CH₃

CH­₃ CH – CH – CH₃

a. 2,3 – dimethyl pent – 2,3 – one b. 3,4 – dimethyl pept – 2 – one

c. 2,3 – dimethyl butane d. 3,4 – dimethyl pentene

1. The alkanoate CH₃CH₂COOC₂H₅ is the product of the reaction between:

(a) ethanoic acid and ethanol (b) ethanoic acid and propanol

(c) propanoic acid and ethanol (d) propanoic acid and propanol

THEORY

ATTEMPT ANY THREE QUESTIONS

1.

A							B
C	D	F	G	H	I	J
K	L	N	O	P	Q	R
S	T

a. Give the letter representing

the strongest oxidizing agent

the strongest reducing agent

a noble gas

an element which forms a +2 ion

an element which forms a +3 ion

b. Write the formula of the compound formed between

F and H

K and Q

c. If the electronic configuration of an ion Q²⁺ is 1s²2s²2p⁶,give the

i. atomic number of Q

II. formula of the chloride of Q

Iii .reason why Q is described as an s-block element.

(1mk each)

2 a. An element X belongs to the same group as sodium but is more reactive.

Suggest with reasons whether X would be an oxidizing agent or a reducing agent.(1mk)

What would be a suitable method of storing X in the Laboratory?(1mk)

Describe briefly what would be observed if a small piece of X were dropped into a trough of cold water which had been coloured with red litmus.(2mks)

Write an equation to show how an oxide of X would react with dilute HCl.(1mk)

bi. State Faraday’s second law of electrolysis.(1mk)

ii. Draw and label a simple cell for the electrolytic purification of copper.(2mks)

iii. Write an equation for the reaction at each electrode in the electrolysis of copper.(2mks)

1. ai. List the two products formed when ethyne burns completely in air.(1mk)

ii. Give the name and structural formula of the second member of the alkyne series.(2mks)

iii. Name the type of reaction involved in the conversion of ethanol to

ethene ii. chloroethane iii. ethanoic acid.(1/2mk each)

What is meant by each of the following terms?

i. saponification (1mk)

ii. Esterification (1mk)

d. List three properties of elements which increase generally across a period in the periodic table.(11/2mks)

e. Give two differences between a chemical reaction and a nuclear reaction.(2mks)

4.a. i. Calculate the Solubility of Na₂CO₃ at 25⁰C, If 20cm3 of its saturated solution at that temperature gave 1.75g of the anhydrous salt.

(C=12,0=16,Na=23)

List three types of salts

What types of salts are ALUMS?

State the function of Alum in water treatment plant.

b. Consider the following reaction at equilibrium:

PCl₅¬˾PCl_3(g)+Cl_2(g)

ΔH=+95kJmol^-1

Write an expression for the equilibrium constant K

Predict the effect of each of the following on the equilibrium position

1. increased pressure

2. increased temperature

3. removal of chlorine

iii. Sketch an energy profile diagram for the forward reaction.

5.a i. Using equations only, show the processes involved in the extraction of ion and the removal of impurities in the blast furnace.

ii. The following reactions occurs when a piece of iron is exposed to moist air for some days.

4Fe_(s)+3O₂+xH₂O_(l)͢͢ 2Fe₂O₃.xH₂O_(S)

State three methods by which this reaction can be prevented.

iii. What is the oxidation number of iron in the product (ii).

b. i. List the characteristic properties of transition metals

ii. Which of the following metals belong to the first transition series?

Chromium, Lead, Iron, Magnesium , Aluminium, Manganese

Copy and complete the following table

Alloy	Constituent elements	One
Bronze
Steel
Duralumin

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