OAU Chemistry 2009/2010 Past Questions

Practice each question, then open it to see the full details.

Question 1

Silver trioxonitrate(V) on heating, gives

A.Ag, N₂O and O₂
B.Ag₂O, N₂ and O₂
C.Ag, O and N₂O
D.Ag, NO₂ and O₂

Objective

Question 2

The most reactive halogen is

A.Cl₂
B.Br₂
C.F₂
D.I₂

Objective

Question 3

0.79g of a gas at s.t.p. occupied a volume of 250cm³. What is the relative molecular mass of the gas? (G.M.V. at s.t.p. = 22.4dm³)

A.17
B.32
C.64
D.71

Objective

Question 4

The relationship between the density (d) of a gas and the rate (r) at which the gas diffuses is

A.r = Kd
B.r = kd^-1/2
C.r = Kd^1/2
D.r = Kd^-1

Objective

Question 5

The pressure exerted by a sample of a gas confined in 5.86dm³ container at 20°C is 4.1 atm. What is the number of moles of the gas in the sample? (R = 0.082dm³atm mol^-1K^-1)

A.1.00
B.2.00
C.3.00
D.4.00

Objective

Question 6

50cm³ of hydrogen are sparked with 100cm³ of oxygen at 110°C and 1 atm. If the whole reaction mixture passes through an alkaline solution pyrogallol, the volume of the residual gas is

A.125cm³
B.100cm³
C.75 cm³
D.50 cm³

Objective

Question 7

Inter - atomic combinations involves the

A.neutrons in the nucleus only
B.protons in the nucleus only
C.electrons in the outer shell only
D.electrons in all the shells.

Objective

Question 8

Which of the following is not a characteristic property of ionic compounds?

A.solubility in polar solvents
B.low melting points
C.conduction of electricity in aqueous solution
D.fast reactions in solution.

Objective

Question 9

The compound with the highest ionic character among the following is

A.PCl₅
B.CCl₄
C.BCl₃
D.CsCl

Objective

Question 10

Why is the hydrogen gas not found in the atmosphere? It readily reacts with

A.carbon(IV) oxide
B.oxygen
C.nitrogen
D.carbon(II) oxide

Objective

Question 11

Apart from water, the other product(s) of the neutralization reaction between NaOH solution and nitrogen(IV) oxide is/are

A.NaNO₂
B.NaNO₃
C.NaNO₃ and HNO₃
D.NaNO² and NaNO³

Objective

Question 12

An acid and its conjugate base

A.are oppositely charged
B.differ only by a hydroxide ion
C.differ only by an electron
D.differ only a proton

Objective

Question 13

A complex salt is

A.KAl(SO₄).12H₂O
B.Cu(NH₃)4Cl₂
C.K₂S₂O₃.5H₂O
D.Mg(OH)Cl.

Objective

Question 14

What happens to the conductivity of an electrolyte as its concentration reduces?

A.increases
B.decreases
C.is unaffected
D.becomes resistivity.

Objective

Question 15

If the cost of electricity required to deposit 1g of aluminum is N4.00, how much would it cost to deposit 24g of copper? [Al = 27, Cu = 64]

A.N27.02
B.N37.02
C.N47.02
D.N57. 02.

Objective

Question 16

The overall reaction in an electrochemical cell is . What is the symbolic represMg_(g) + Cu²⁺_(aq) → Mg²⁺_(aq) + Cu_(s) entation of the cell?

A.Mg_(s)/Mg_(aq)²⁺ || Cu_(aq)²⁺/Cu_(s)
B.Mg_(aq)/Mg_(s)²⁺ || Cu_(s)²⁺/Cu_(aq)
C.Cu_(s)²⁺/Cu_(s) || Mg_(s)/Mg_(aq)²⁺
D.Cu_(s)/Cu_(aq)²⁺ || Mg_(aq)²⁺/Mg_(s)

Objective

Question 17

Which of the following metals can be used as sacrificial cathode for preventing corrosion of a length of iron pipe?

A.Ag
B.Cu
C.Mg
D.Mn.

Objective

Question 18

A particle that contains 8 protons, 9 neutrons and 7 electrons could be written as

A.¹⁶₈O
B.¹⁷₈O^-
C.¹⁷₉O^-
D.¹⁷₈O⁺

Objective

Question 19

The decreasing order of the magnitude of energy changes is

A.phase, chemical, nuclear
B.chemical, nuclear, phase
C.nuclear, phase, chemical
D.nuclear, chemical, phase

Objective

Question 20

0.92g of ethanol raised the temperature of 100g of water from 298K to 312.3K when burned completely. What is the heat of combustion of ethanol? [C = 12; H = 1; 0 = 16; specific heat capacity of water = 4.2Jg^-1K]

A.+300KJmol
B.+3000KJmol
C.-300KJmol
D.-3000KJmol

Objective

Question 21

The highest level of molecular disorderliness is found in

A.ice at -10°C
B.water at 100°C
C.steam at 100°C
D.ice at 0°C.

Objective

Question 22

A reaction is spontaneous at all temperature if

A.ΔG=0
B.ΔG>0
C.ΔS<0 and ΔH>0
D.ΔS>0 and ΔH<0

Objective

Question 23

Which of the following reactions of marble with 100cm³ of 0.100moldm³. HCl is fastest?

A.5g of marble lump at 50°C
B.5g of marble powder at 50°C
C.5g of marble powder at 25°C
D.5g of marble lump 25°C

Objective

Question 24

A_(g) + 2B_(g) → C_(g) In the reaction represented by the equation above, the rate of appearance of C is found experimentally to be independent of the concentration of A and to increase four folds when the concentration of B is doubled. The rate law for the reaction is

A.Rate = K[A]⁰[B]⁴
B.Rate = K[A]⁰[B]²
C.Rate = K[A][B]²
D.Rate = K[A]²[B]⁰

Objective

Question 25

How is the equilibrium constant for the forward reaction of an equilibrium (K_f) related to that of the reverse reaction (K_r)?

A.(K_r) is the additive inverse of (K_f)
B.(K_r) is the multiplicative inverse of (Kf)
C.(K_r) is the same as (K_f)
D.the product of (K_r) and (K_f) is zero

Objective

Question 26

What is the concentration of OH- ions of an aqueous solution of pH 4.4?

A.9.600 x 10^-10moldm^-3
B.2.512 x 10^-10moldm^-3
C.9.600 x 10^-11moldm^-3
D.2.512 X 10^-11moldm^-3

Objective