JAMB UTME - Chemistry - 2019

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Question 3 Report

When the end alkyl groups of ethyl ethanoate are interchanged, the compound formed is

propylmethanoate

ethylpropanoate

methyl ethanoate

methyl propanoate

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Question 4 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 5 Report

The velocity, V of a gas is related to its mass, M by (k = proportionality constant)

V =

\frac{k}{M}

V =

\frac{k}{M^{\frac{1}{2}}}

V =

k M^{2}

V =

(\frac{k}{M})^{\frac{1}{2}}

Answer Details

Recall:
V =

\sqrt{\frac{3 R T}{M}}

∴ V \propto \frac{1}{\sqrt{M}}

V = \frac{k}{\sqrt{M}}

V =

\frac{k}{M^{\frac{1}{2}}}

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

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Question 6 Report

Which of the following alkaline metals react more quickly spontaneously with water?

Calcium

Beryllium

Magnesium

Strontium

Answer Details

The alkaline earth metals (Be, Mg, Ca, Sr, Ba, and Ra) are the second most reactive metals in the periodic table, and, like the Group 1 metals, have increasing reactivity in the higher periods. Beryllium (Be) is the only alkaline earth metal that does not react with water or steam, even if metal is heated to red heat. Additionally, beryllium has a resistant outer oxide layer that lowers its reactivity at lower temperatures.

Magnesium shows insignificant reaction with water, but burns vigorously with steam or water vapor to produce white magnesium oxide and hydrogen gas:

Mg(s) + 2 H2O(l) ⟶ Mg(OH)2(s) + H2(g)

A metal reacting with cold water will produce metal hydroxide. However, if a metal reacts with steam, like magnesium, metal oxide is produced as a result of metal hydroxides splitting upon heating.

The hydroxides of calcium, strontium and barium are only slightly water-soluble but produce sufficient hydroxide ions to make the environment basic, giving a general equation of:

M(s) + 2 H2O(l) ⟶ M(OH)2(aq) + H2(g)

Order of reactivity	Metal	Reactions with water or steam
most reactive	potassium (K)	very vigorous reaction with cold water
↑	sodium (Na)	vigorous reaction with cold water
↓	calcium (Ca)	less vigorous reaction with cold water
least reactive	magnesium (Mg)	slow reaction with cold water, vigorous with steam

If metals react with cold water, hydroxides are produced.
Metals that react with steam form oxides.
Hydrogen is always produced when a metal reacts with cold water or steam.

Read lesson note on Metals And Their Compounds (JAMB)

Read lesson note on Organic Compounds (JAMB)

Metals And Their Compounds

Organic Compounds

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Question 7 Report

What technique is suitable for separating a binary solution of potassium chloride and potassium trioxochlorate (V)?

Fractional crystallization

Fractional distillation

Filtration

Evaporation

Separation Of Mixtures And Purification Of Chemical Substances

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Question 8 Report

What volume of 0.100M sodium trioxonitrate (V) solution contains 5g of solute.

[Na = 23, N = 14, O = 16]

1.7 litres

0.420 litres

0.588 litres

2.35 litres

Stoichiometry And Chemical Reactions

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Question 9 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 10 Report

How many alkoxyalkanes can be obtained from the molecular formula $ \mathrm{C_4H_{10}O} $?

4

2

1

3

Acids, Bases And Salts (Nigeria Only)

Chemical Equilibria

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Question 11 Report

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

methylpropanoate

ethylethanoate

ethylpropanoate

methylethanoate

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Question 12 Report

The part of the total energy of a system that accounts for the useful work done in a system is known as

Enthalpy change

None of the above

Gibb's free energy

Entropy

Energy Changes

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Question 13 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 14 Report

A solution X, on mixing with $ \mathrm{AgNO_3} $ solution gives a white precipitate soluble in aqueous $ \mathrm{NH_3} $, a solution Y, when also added to X, also gives a white precipitate which is soluble when heated solutions X and Y respectively contain

Al

^{3 +}

, Cl

^{-}

Hg

^{+}

, SO

_{4}^{2 -}

Pb

^{2 +}

, Cl

^{-}

Ag

^{+}

, SO

_{4}^{2 -}

Chemistry Of Carbon Compounds (Ghana Only)

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Question 15 Report

At 27°C, 58.5g of sodium chloride is present in 250cm$^3$ of a solution. The solubility of sodium chloride at this temperature is?

(molar mass of sodium chloride = 111.0gmol$^{-1}$)

2.0 moldm

^{- 3}

0.25 moldm

^{- 3}

1.0 moldm

^{- 3}

0.5 moldm

^{- 3}

Answer Details

Given the Mass of the salt = 58.5g
Volume = 250 cm

^{3}

= 0.25 dm

^{3}

Mass concentration =

\frac{M a s s}{V o l u m e}

=

\frac{58.5}{0.25}

= 234 gdm

^{- 3}

Solubility (in moldm

^{- 3}

=

\frac{234}{111}

= 2.11 moldm

^{- 3}

≊

2.0 moldm

^{- 3}

Read lesson note on Solubility Of Substances (Ghana Only) (WAEC)

Solubility Of Substances (Ghana Only)

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Question 16 Report

Burning magnesium ribbon in air removes which of the following

(i) oxygen (ii) nitrogen (iii) argon and (iv) carbon(iv)oxide?

i and iv only

i, ii, iii and iv only

i only

i and ii only

Separation Of Mixtures And Purification Of Chemical Substances

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Question 17 Report

The IUPAC nomenclature of the compound

$\mathrm{H_3C - CH(CH_3) - CH(CH_3) - CH_2 - CH_3}$

3,4- dimethylhexane

2,3- dimethyl pentane

2- ethyl hexane

2,3- dimethylhexane

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Question 18 Report

Which of the following conditions will most enhance the spontaneity of a reaction?

Δ

H is negative and greater than T

Δ

S

Δ

H is negative and

Δ

S = 0

Δ

H is positive and less than T

Δ

S

Δ

H is positive and equal to T

Δ

S

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Question 19 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 20 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 21 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 22 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 23 Report

Which quantum divides shells into orbitals?

Spin

Principal

Azimuthal

Magnetic

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Question 24 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 25 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 26 Report

The oxidation state(s) of nitrogen in ammonium nitrite is/are

-3, +3

+5

-3, +5

-3

Answer Details

Ammonium nitrite = NH

_{4}

NO

_{2}

NH

_{4}^{+}

: Let the oxidation number of Nitrogen = x
x + 4 = 1

⟹

x = 1 - 4
x = -3
NO

_{2}^{-}

: x - 4 = -1
x = -1 + 4

⟹

x = +3.
The oxidation numbers for Nitrogen in Ammonium Nitrite = -3, +3.

Read lesson note on Oxidation And Reduction (JAMB)

Oxidation And Reduction

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Question 27 Report

Which of the following gases contains the least number of atoms at s.t.p?

1 mole of butane

4 moles of chlorine

3 moles of ozone

7 moles of argon

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Question 28 Report

Which of the following sets of operation will completely separate a mixture of sodium chloride, sand and iodine?

addition of water, filtration, evaporation to dryness and sublimation

filtration, evaporation to dryness, addition of water and sublimation

sublimation, filtration, evaporation and addition of water

sublimation, addition of water, filtration and evaporation to dryness

Separation Of Mixtures And Purification Of Chemical Substances

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Question 29 Report

Which two gases can be used for the demonstration of the fountain experiment?

SO

_{3}

and NH

_{3}

SO

_{2}

and NH

_{3}

HCl and NH

_{3}

SO

_{2}

and HCl

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Question 30 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 31 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 32 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 33 Report

Which of the following represents the kind of bonding present in ammonium chloride?

ionic only

covalent only

ionic and dative covalent

dative covalent

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Question 34 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 35 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 36 Report

Which important nitrogen-containing compound is produced in Haber's process?

NH

_{3}

NO

_{2}

NO

HNO

_{3}

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Question 37 Report

Hydrocarbons which will react with Tollen's reagent conform to the general formula

C

_{n}

H

_{2 n}

C

_{n}

H

_{2 n + 2}

C

_{n}

H

_{2 n - 2}

C

_{n}

H

_{2 n + 1}

OH

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Question 38 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}