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JAMB UTME - Chemistry - 2019

Question 1 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 5 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

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 6 Report

The emission of two successive beta particles from the nucleus \( {}^{32}_{15}\mathrm{P} \) will produce

_{14}^{30}

Si

_{13}^{32}

Al

_{17}^{32}

Cl

_{16}^{32}

S

Answer Details

Explanation:

_{15}^{32}

P

\to

2

_{- 1}^{0}

e +

_{b}^{a}

X
32 = 2(0) + a
a = 32
15 = 2(-1) + b
b = 15 + 2
b = 17

∴

_{b}^{a}

X =

_{17}^{32}

Cl

Read lesson note on Structure Of The Atom (WAEC)

Structure Of The Atom

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Question 9 Report

The following are isoelectronic ions except

Na

^{+}

Mg

^{2 +}

Si

^{2 +}

O

^{2 +}

Answer Details

Two or more ions are said to be isoelectronic if they have the same electronic structure and the same number of valence electrons.
Na

^{+}

= 10 electrons = 2, 8
Mg

^{2 +}

= 10 electrons = 2,8
O

^{2 -}

= 10 electrons = 2,8
Si

^{2 +}

= 12 electrons = 2,8,2

⟹

Si

^{2 +}

is not isoelectronic with the rest.

Read lesson note on Acids, Bases And Salts (Nigeria Only) (WAEC)

Read lesson note on Atomic Structure And Bonding (JAMB)

Acids, Bases And Salts (Nigeria Only)

Atomic Structure And Bonding

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Question 11 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

Y

_{2}

X

_{3}

X

_{2}

Y

_{3}

View Answer

Question 12 Report

The electronic configuration of element Z is \(1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^1\). What is the formula of the compound formed between Z and tetraoxosulphate (VI) ion.

Z

_{3}

(SO

_{4}

)

_{2}

ZSO

_{4}

Z

_{2}

SO

_{4}

Z

_{2}

(SO

_{4}

)

_{3}

Answer Details

Z = 1s

^{2}

2s

^{2}

2p

^{6}

3s

^{2}

3p

^{1}

∴

We have Z

^{3 +}

and SO

_{4}^{2 -}

The reaction : Z

^{3 +}

+ SO

_{4}^{2 -}

\to

Z

_{2}

(SO

_{4}

)

_{3}

.

Read lesson note on Atomic Structure And Bonding (JAMB)

Atomic Structure And Bonding

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Question 17 Report

When chlorine water is exposed to bright sunlight, the following products are formed

HCl

_{(a q)}

and Cl

_{2}

HOCl

_{(a q)}

and Cl

_{2}

HCl

_{(a q)}

and O

_{2}

HOCl

_{(a q)}

and O

_{2}

Chemistry Of Carbon Compounds (Ghana Only)

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Question 23 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

Kinetic Theory Of Matter And Gas Laws

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Question 25 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

View Answer

Question 26 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

View Answer

Question 27 Report

The hybridization in the compound \( \mathrm{CH_3-CH_2-C\equiv H} \) is

sp

^{3}

and sp

sp

sp

^{2}

sp

^{3}

and sp

^{2}

Answer Details

The hybridization in a and b is sp

^{3}

hybridization while in c and d is sp hybridization.

View Answer

Question 28 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

Kinetic Theory Of Matter And Gas Laws

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Question 29 Report

By what amount must the temperature of 200cm\(^{3}\) of Nitrogen at 27°C be increased to double the pressure if the final volume is 150cm\(^{3}\) (Assume ideality)

150°C

177°C

75°C

120°C

Answer Details

Using the ideal gas law and equation:

\frac{P_{1} V_{1}}{T_{1}} = \frac{P_{2} V_{2}}{T_{2}}

\frac{P_{1} \times 200 {cm}^{3}}{300 K} = \frac{2 P \times 150 {cm}^{3}}{T_{2}}

Cross multiply:

T_{2} = \frac{300 \times 150 \times 2 P}{200 \times P}

= 450 K

or

177^{\circ} C

Don't forget to convert to

^{\circ} C

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

Kinetic Theory Of Matter And Gas Laws

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Question 31 Report

A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm³ of CO₂ and 54g of water. The hydrocarbon should be

C

_{6}

H

_{6}

C

_{4}

H

_{10}

C

_{5}

H

_{10}

C

_{4}

H

_{6}

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 35 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 36 Report

What mass of magnesium would be obtained by passing a current of 2 amperes for 2 hours, through molten magnesium chloride?
[1 faraday = 96500C, Mg = 24]

1.12g

4.48g

1.80g

2.00g

Answer Details

Current (I) = 2A; Time (t) = 2 hours = 7200 secs
Q = It
= 2 x 7200 = 14400C
1 F = 96500C
x = 14400C
x =

\frac{14400}{96500}

= 0.15F
Mg

^{2 +}

+ 2e

^{-}

\to

Mg
2F

\to

24g
0.15F

\to

x
2x = 24 x 0.15
x =

\frac{24 \times 0.15}{2}

= 1.8g

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

Read lesson note on Electrolysis (JAMB)

Chemical Kinetics And Equilibrium Systems (Ghana Only)

Electrolysis

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Question 39 Report

Which of the following describes the chemical property of acids?

None of the above

Acid + XCO

_{3}

\to

Salt + H

_{2}

O + NH

_{3}

Acid + NaOH

\to

Normal salt + CO

_{2}

Acid + X

_{n}

CO

_{3}

\to

Salt + H

_{2}

O + CO

_{2}

Acids, Bases And Salts

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