JAMB UTME - Chemistry - 2019

Acids, Bases And Salts (Nigeria Only)

Chemical Equilibria

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Question 4 Report

Which of the following is a physical change?

Exposing white phosphorus to air

Burning kerosene

Dissolving calcium in water

Freezing ice cream

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Question 5 Report

Which of the following could not be alkane?

C

_{4}

H

_{10}

C

_{5}

H

_{12}

C

_{7}

H

_{14}

C

_{8}

H

_{18}

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Question 6 Report

Which of the following reactions is an oxidation process?

2H

^{+}

+ 2e

^{-}

\to

H

_{2}

2O

^{2 -}

+ 4e

^{-}

\to

O

_{2}

OCl

^{-}

+ H

_{2}

O + 2e

^{-}

\to

2OH

^{-}

+ Cl

^{-}

Cl + e

^{-}

\to

Cl

^{-}

Oxidation And Reduction

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Question 7 Report

The IUPAC name of the compound $\mathrm{CF_3CHBrCl}$ is

2-chloro-2-bromo-1,1,1-trifluoroethane

2-bromo-2-chloro-1,1,1-trifluoroethane

1-bromo-1-chloro-2,2,2-trifluoroethane

1,1,1-trifluoro-2-bromo-2-chloroethane

Periodic Chemistry (Ghana Only)

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Question 8 Report

When ammonia and hydrogen ion bond together to form ammonium ion, the bond formed is called

electrovalent bond

co-ordinate bond

ionic bond

covalent bond

Oxidation And Reduction

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Question 9 Report

Which of the following is a set of neutral oxides?

N

_{2}

O, H

_{2}

O, CO

N

_{2}

O, SO

_{2}

, CO

N

_{2}

O, Na

_{2}

O, ZnO

N

_{2}

O, SO

_{3}

, NO

Oxidation And Reduction

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Question 10 Report

Which of the following will give a precipitate with an aqueous solution of copper (I) chloride?

But-2-ene

But-1-ene

But-2-yne

But-1-yne

Rates Of Chemical Reaction

Chemical Bonds (Ghana Only)

Redox Reactions

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Question 11 Report

Elements in the periodic table are arranged in the order of their

atomic numbers

metallic character

mass number

relative atomic mass

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Question 12 Report

The heat of formation of ethene, $ \mathrm{C_2H_4} $ is 50 $ \mathrm{kJmol^{-1}} $, and that of ethane, $ \mathrm{C_2H_6} $ is -82$ \mathrm{kJmol^{-1}} $. Calculate the heat evolved in the process:

\[ \mathrm{C_2H_4 + H_2 \rightarrow C_2H_6} \]

-122kJ

-132kJ

-88kJ

-60kJ

Energy Changes

Stoichiometry And Chemical Reactions

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Question 13 Report

If the cost of electricity required to discharge 10g of an ion $X^{3+}$ is N20.00, how much would it cost to discharge 6g of ion $Y^{2+}$?

[1 faraday = 96,500C, atomic masses are X = 27, Y = 24]

N10.00

N6.00

N20.00

N9.00

Answer Details

X

^{3 +}

+ 3e

^{-}

\to

X
3F = 27g
xF = 10g

\frac{x}{3} = \frac{10}{27} ⟹ x = \frac{10}{9} F

\frac{10}{9}

F

\equiv

N20.00
1F is equivalent to x

\frac{1}{\frac{10}{9}} = \frac{x}{20}

\frac{9}{10} = \frac{x}{20} ⟹ x = N 18.00

1F is equivalent to N18.00.
Y

^{2 +}

+ 2e

^{-}

\to

Y
2F = 24g
xF = 6g
x =

\frac{6 \times 2}{24} = \frac{1}{2} F

1F = N18.00

\frac{1}{2}

F =

\frac{1}{2} \times N 18.00

= N9.00

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Question 14 Report

In the reaction between sodium hydroxide and tetraoxosulphate (VI) solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralize 10cm$^{3}$ of 1.25 molar tetraoxosulphate (vi) acid?

25cm

^{3}

10cm

^{3}

20cm

^{3}

50cm

^{3}

Answer Details

Equation of reaction : 2NaOH + H

_{2}

SO

_{4}

→ Na

_{2}

SO

_{4}

+ 2H

_{2}

O

Concentration of a base, CB = 0.5M

Volume of acid, V $_{A}$ = 10cm $^{3}$

Concentration of an acid, C $_{A}$ = 1.25M

Volume of base, V $_{B}$ = ?

Recall:
$\frac{C_{A} V_{A}}{C_{B} V_{B}} = \frac{n_{A}}{n_{B}}$ ... (1)
N.B: From the equation,
$\frac{n_{A}}{n_{B}} = \frac{1}{2}$

From (1)
$\frac{1.25 \times 10}{0.5 \times V_{B}} = \frac{1}{2}$
$\frac{12.5}{0.5 V_{B}} = \frac{1}{2}$
25 = 0.5V $_{B}$

VB = 50.0 cm $^{3}$

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

Stoichiometry And Chemical Reactions

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Question 15 Report

The combustion of carbon(ii)oxide in oxygen can be represented by equation.

$2\mathrm{CO} + \mathrm{O}_2\ ?\ 2\mathrm{CO}_2$

Calculate the volume of the resulting mixture at the end of the reaction if $50\mathrm{cm}^3$ of carbon(ii)oxide was exploded in $100\mathrm{cm}^3$ of oxygen

75cm

^{3}

125cm

^{3}

100cm

^{3}

50cm

^{3}

Stoichiometry And Chemical Reactions

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Question 16 Report

Hydrogen diffused through a porous plug

thrice as fast as oxygen

at the same speed as oxygen

four times as fast as oxygen

twice as fast as oxygen

Acids, Bases And Salts (Nigeria Only)

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Question 17 Report

$200\text{cm}^3$ of $0.50\text{mol}/\text{dm}^3$ solution of calcium hydrogen trioxocarbonate (IV) is heated. The maximum weight of solid precipitated is

10g

25g

20g

15g

Answer Details

To solve this problem, we need to use the concept of stoichiometry and the solubility product constant (Ksp) of calcium hydrogen trioxocarbonate (IV). First, we need to write the balanced equation for the reaction that occurs when the solution of calcium hydrogen trioxocarbonate (IV) is heated: Ca(HCO3)2(s) → CaCO3(s) + H2O(g) + CO2(g) From the balanced equation, we can see that 1 mole of calcium hydrogen trioxocarbonate (IV) produces 1 mole of calcium carbonate. Therefore, we need to determine the number of moles of calcium hydrogen trioxocarbonate (IV) in the solution: Number of moles = concentration x volume Number of moles = 0.50 mol/dm³ x 0.2 dm³ Number of moles = 0.1 mol Since 1 mole of calcium hydrogen trioxocarbonate (IV) produces 1 mole of calcium carbonate, the number of moles of calcium carbonate produced will also be 0.1 mol. Next, we need to use the solubility product constant (Ksp) of calcium carbonate to determine the maximum amount of solid that can be precipitated: Ksp = [Ca²⁺][CO3²⁻] Ksp = 3.3 x 10⁻⁹ (at 25°C) At the maximum amount of solid precipitated, all the calcium carbonate formed will have precipitated, and the concentration of calcium ions and carbonate ions will be equal. Therefore, we can assume that the concentration of calcium ions and carbonate ions is both x. Substituting into the Ksp expression: Ksp = x² 3.3 x 10⁻⁹ = x² x = 5.74 x 10⁻⁵ mol/dm³ The mass of calcium carbonate precipitated can now be calculated: Mass = number of moles x molar mass Mass = 0.1 mol x 100.1 g/mol Mass = 10.01 g Therefore, the maximum weight of solid precipitated is approximately 10 g. Note that this calculation assumes that all the calcium carbonate precipitated as a solid, which may not always be the case in a real-world experiment. Additionally, this calculation does not take into account any losses due to filtration or other experimental errors.

Read lesson note on Kinetic Theory Of Matter And Gas Laws (JAMB)

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Question 18 Report

Which of the following properties increases from left to right along the period but decreases down the group in the Periodic Table?

I. Atomic Number ii. Ionization energy iii. Metallic character iv. Electron affinity

ii and iii only

ii and iv only

iii and iv only

i and ii only

Periodic Chemistry (Nigeria Only)

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Question 19 Report

Which of the following metals is the most essential in the regulation of blood volume, blood pressure and osmotic equilibrium?

Zinc

Manganese

Sodium

Iron

Metals And Their Compounds

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Question 20 Report

The shapes of water, ammonia, carbon (iv) oxide and methane are respectively

linear, tetrahedral, angular and pyramidal

angular, pyramidal, linear and tetrahedral

pyramidal, linear, tetrahedral and angular

tetrahedral, angular, pyramidal and linear

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Question 21 Report

For the general equation of the nature

XP + yQ ⇌ mR + nS, the expression for the equilibrium constant is

k[P]

^{x}

[Q]

^{y}

\frac{m [R] [S]}{x [P] y [Q]}

\frac{[P]^{x} [Q]^{y}}{[R]^{m} [S]^{n}}

\frac{[R]^{m} [S]^{n}}{[P]^{x} [Q]^{y}}

Answer Details

The expression for the equilibrium constant for the general equation XP + yQ ⇌ mR + nS is: Kc = [R]m[S]n / [P]x[Q]y where Kc is the equilibrium constant, [R] and [S] are the concentrations of the products, and [P] and [Q] are the concentrations of the reactants, all raised to the stoichiometric coefficients (m, n, x, y) in the balanced equation. This equation is known as the equilibrium constant expression and it represents the ratio of the concentrations of the products and reactants at equilibrium for a particular chemical reaction. The equilibrium constant is a measure of how far a reaction proceeds towards completion, with a larger value indicating a greater extent of reaction. The equilibrium constant expression is derived from the law of mass action, which states that the rate of a chemical reaction is proportional to the product of the concentrations of the reactants raised to their stoichiometric coefficients. At equilibrium, the rates of the forward and reverse reactions are equal, and the equilibrium constant expression represents the ratio of the rate constants for these two reactions. Therefore, the correct expression for the equilibrium constant for the general equation XP + yQ ⇌ mR + nS is Kc = [R]m[S]n / [P]x[Q]y.

Read lesson note on Chemical Kinetics And Equilibrium Systems (Ghana Only) (WAEC)

Read lesson note on Chemical Equilibria (JAMB)

Chemical Kinetics And Equilibrium Systems (Ghana Only)

Chemical Equilibria

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Question 22 Report

The reaction $2H_2S + SO_2 \rightarrow 3S + 2H_2O$ is

not a redox reaction because there is no oxidant in the reaction

not a redox reaction because there is no reductant in the reaction

a redox reaction in which H

_{2}

S is the oxidant and SO

_{2}

is the reductant

a redox reaction in which SO

_{2}

is the oxidant and H

_{2}

S is the reductant

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Question 23 Report

A secondary alkanol can be oxidized to give an

alkanone

alkyne

alkanoic acid

alkanal

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Question 24 Report

The IUPAC name for $ \mathrm{CH_3CH_2COOCH_2CH_3} $ is

methylpropanoate

ethylethanoate

ethylpropanoate

methylethanoate

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Question 25 Report

Which of the following statements does not show Rutherford's account of Nuclear Theory? An atom contains a region

which contains protons and neutrons

which is positively charged

which is massive and can cause deflection of a few projectiles

which is very large and in which close to 98% of projectiles pass undeflected

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Question 26 Report

An element Z contains 80% of $ {}^{16}_{8}\mathrm{Z} $ and 20% of $ {}^{18}_{8}\mathrm{Z} $. Its relative atomic mass is

16.2

17.6

16.0

16.4

Answer Details

R.A.M of Z =

16 (\frac{80}{100}) + 18 (\frac{20}{100})

=

12.8 + 3.6

= 16.4

Read lesson note on Separation Of Mixtures And Purification Of Chemical Substances (JAMB)

Read lesson note on Atomic Structure And Bonding (JAMB)

Separation Of Mixtures And Purification Of Chemical Substances

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Question 27 Report

A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180. Find the molecular formula.

[H = 1, C = 12, O = 16]

C

_{3}

H

_{6}

O

_{3}

C

_{6}

H

_{6}

O

_{3}

C

_{6}

H

_{12}

O

_{6}

CH

_{2}

O

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Question 28 Report

Which process(es) is/are involved in the turning of starch iodide paper blue-black by chlorine gas?

chlorine attacks the starch to give the blue-black color

chlorine attacks the iodide ion to give the blue-black color

chlorine oxidizes the iodide ion to produce iodine which attacks the starch to give the blue-black color

iodine attacks the starch to give the blue-black color

Energy And Energy Changes

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Question 29 Report

Which of the following factors will speed up the rate of evolution of carbon (iv) oxide in the reaction below?

$2HCl + CaCO_3 \rightarrow CaCl_2 + H_2O + CO_2$

Increasing the concentration of the acid

Increasing the surface area of CaCO

_{3}

A and B

Reducing the concentration of the acid

Oxidation And Reduction

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Question 30 Report

Elements X and Y have electronic configurations $1s^2 2s^2 2p^4$ and $1s^2 2s^2 2p^6 3s^2 3p^1$ respectively. When they combine, the formula of the compound formed is

XY

X

_{2}

Y

_{2}

X

_{3}

X

_{2}

Y

_{3}

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Question 31 Report

The two ions responsible for hardness in water are

Ca

^{2 +}

and / or Mg

^{2 +}

K

^{+}

and / or Mg

^{2 +}

Ca

^{2 +}

and / or Li

^{+}

Ca

^{2 +}

and / or Na

^{+}

Solubility

Water

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Question 32 Report

Which of the following is the best starting material for the preparation of oxygen? Heating of trioxonitrate (v) with

Pb

Zn

Ca

Na

Chemical Combination

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Question 33 Report

Which quantum divides shells into orbitals?

Spin

Principal

Azimuthal

Magnetic