Which of the following does not support the fact that air is a mixture?

the constituents of air are in a fixed proportion by mass

it cannot be represented with a chemical formula

the constituents of air can be separated by physical by physical means

In the reaction: M + N → P ΔH = +Q kJWhich of the following would increase the concentration of the product?

Increasing the concentration of P

Which of the following is a physical change?

Exposing white phosphorus to air

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

angular, pyramidal, linear and tetrahedral

linear, tetrahedral, angular and pyramidal

angular, pyramidal, linear and tetrahedral

pyramidal, linear, tetrahedral and angular

tetrahedral, angular, pyramidal and linear

JAMB UTME - Chemistry - 2019 | Green Bridge CBT

Swali 1 Ripoti

A radioactive nucleus has a half-life of 20 years, starting with 100,000 particles, how many particles will be left exactly at the end of 40 years

75,000 particles

35,000 particles

25,000 particles

50,000 particles

Kinetic Theory Of Matter And Gas Laws

Tazama Jibu

Swali 2 Ripoti

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

Tazama Jibu

Swali 3 Ripoti

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

NH

_{3}

NO

_{2}

NO

HNO

_{3}

Kinetic Theory Of Matter And Gas Laws

Tazama Jibu

Swali 4 Ripoti

$ \mathrm{SO_3} $ is not directly dissolved in water in the industrial preparation of $ \mathrm{H_2SO_4} $ by the contact process because

SO

_{3}

is an acidic gas

Acid is usually added to water and not water to acid

The reaction between SO

_{3}

and water is violently exothermic

SO

_{3}

does not dissolve readily in water

Acids, Bases And Salts

Tazama Jibu

Swali 5 Ripoti

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

Tazama Jibu

Swali 6 Ripoti

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

Tazama Jibu

Swali 7 Ripoti

A cell shorthand notation can be written as $A / A^{+} // B^{2+} / B$. The double slash in the notation represents the

electrolyte

electrodes

salt bridge

solid - liquid interface

Electrolysis

Tazama Jibu

Swali 8 Ripoti

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

Maelezo ya Majibu

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

Tazama Jibu

Swali 9 Ripoti

Which of the following could not be alkane?

C

_{4}

H

_{10}

C

_{5}

H

_{12}

C

_{7}

H

_{14}

C

_{8}

H

_{18}

Chemistry Of Carbon Compounds (Nigeria Only)

Tazama Jibu

Swali 10 Ripoti

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

-3, +3

+5

-3, +5

-3

Maelezo ya Majibu

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.

Soma maelezo ya somo kwenye Oxidation And Reduction (JAMB)

Oxidation And Reduction

Tazama Jibu

Swali 11 Ripoti

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

Calcium

Beryllium

Magnesium

Strontium

Maelezo ya Majibu

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.

Soma maelezo ya somo kwenye Metals And Their Compounds (JAMB)

Soma maelezo ya somo kwenye Organic Compounds (JAMB)

Metals And Their Compounds

Organic Compounds

Tazama Jibu

Swali 12 Ripoti

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}

Kinetic Theory Of Matter And Gas Laws

Stoichiometry And Chemical Reactions

Tazama Jibu

Swali 13 Ripoti

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

Maelezo ya Majibu

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

Soma maelezo ya somo kwenye Chemical Kinetics And Equilibrium Systems (Ghana Only) (WAEC)

Soma maelezo ya somo kwenye Electrolysis (JAMB)

Chemical Kinetics And Equilibrium Systems (Ghana Only)

Electrolysis

Tazama Jibu

Swali 14 Ripoti

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

Chemistry Of Carbon Compounds (Nigeria Only)

Tazama Jibu

Swali 15 Ripoti

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

Tazama Jibu

Swali 16 Ripoti

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}}

Maelezo ya Majibu

Recall:
V = $\sqrt{\frac{3 R T}{M}}$
$∴ V \propto \frac{1}{\sqrt{M}}$
$V = \frac{k}{\sqrt{M}}$
V = $\frac{k}{M^{\frac{1}{2}}}$

Soma maelezo ya somo kwenye Kinetic Theory Of Matter And Gas Laws (JAMB)

Kinetic Theory Of Matter And Gas Laws

Tazama Jibu

Swali 17 Ripoti

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

Kinetic Theory Of Matter And Gas Laws

Acids, Bases And Salts (Nigeria Only)

Tazama Jibu

Swali 18 Ripoti

If acidified Potassium Dichromate(VI) ($\mathrm{K_2Cr_2O_7}$) acts as oxidizing agent, color changes from

yellow to green

orange to green

yellow to red

orange to red

Oxidation And Reduction

Tazama Jibu

Swali 19 Ripoti

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

Kinetic Theory Of Matter And Gas Laws

Tazama Jibu

Swali 20 Ripoti

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

sp

^{3}

and sp

sp

^{2}

sp

^{3}

and sp

^{2}

Maelezo ya Majibu

The hybridization in a and b is sp $^{3}$ hybridization while in c and d is sp hybridization.

Tazama Jibu

Swali 21 Ripoti

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

Maelezo ya Majibu

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

Soma maelezo ya somo kwenye Structure Of The Atom (WAEC)

Structure Of The Atom

Tazama Jibu

Swali 22 Ripoti

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)

Tazama Jibu

Swali 23 Ripoti

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

4

2

1

3

Chemistry Of Carbon Compounds (Nigeria Only)

Acids, Bases And Salts (Nigeria Only)

Chemical Equilibria

Tazama Jibu

Swali 24 Ripoti

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

methylpropanoate

ethylethanoate

ethylpropanoate

methylethanoate

Chemistry Of Carbon Compounds (Nigeria Only)

Tazama Jibu

Swali 25 Ripoti

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

Chemistry Of Carbon Compounds (Nigeria Only)

Tazama Jibu

Swali 26 Ripoti

Consider the reaction: $ \mathrm{A + 2B(g) \rightleftharpoons 2C + D(g)} $ ($ \Delta H = +\mathrm{ve} $)

What will be the effect of decrease in temperature on the reaction?

Rate of backward reaction will increase

The equilibrium constant will shift

Rates of forward and backward reactions are not affected

Rate of forward reaction will increase

Chemical Equilibria

Tazama Jibu

Swali 27 Ripoti

Consider the equation below:

$\mathrm{Cr_2O_7^{2-} + 6Fe^{2+} + 14H^+ \rightarrow 2Cr^{3+} + 6Fe^{3+} + 7H_2O}$.

The oxidation number of chromium changes from

+5 to +3

+6 to +3

-2 to +3

+7 to +3

Maelezo ya Majibu

Cr $_{2}$ O $_{7}^{2 -}$ + 6Fe $^{2 +}$ + 14H $^{+}$ $\to$ 2Cr $^{3 +}$ + 6Fe $^{3 +}$ + 7H $_{2}$ O
The oxidation of Cr in Cr $_{2}$ O $_{7}^{2 -}$ :
Let the oxidation of Cr = x;
2x + (-2 x 7) = -2 $⟹$ 2x - 14 = -2
2x = 12 ; x = +6
Hence, the change in oxidation of Cr = +6 to +3

Soma maelezo ya somo kwenye Oxidation And Reduction (JAMB)

Oxidation And Reduction

Tazama Jibu

Swali 28 Ripoti

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)

Tazama Jibu

Swali 29 Ripoti

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

Maelezo ya Majibu

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 $^{\circ} C$

Soma maelezo ya somo kwenye Kinetic Theory Of Matter And Gas Laws (JAMB)

Kinetic Theory Of Matter And Gas Laws

Tazama Jibu

Swali 30 Ripoti

$ \mathrm{Na_2CO_3 + 2HCl \rightarrow 2NaCl + H_2O + CO_2} $

The indicator most suitable for this reaction should have a pH equal to

5

7

3

9

Acids, Bases And Salts

Tazama Jibu

Swali 31 Ripoti

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

ionic only

covalent only

ionic and dative covalent

dative covalent

Tazama Jibu

Swali 32 Ripoti

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)

Tazama Jibu

Swali 33 Ripoti

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

Atomic Structure And Bonding

Tazama Jibu

Swali 34 Ripoti

Sulphur exists in six forms in the solid state. This property is known as

Isomerism

Allotropy

Isotopy

Isomorphism

Non-metals And Their Compounds

Tazama Jibu

Swali 35 Ripoti

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

Tazama Jibu

Swali 36 Ripoti

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

Tazama Jibu

Swali 37 Ripoti

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}

Maelezo ya Majibu

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 $^{- 3}$