JAMB UTME - Chemistry - 2019

Wo Idahun

Ajụjụ 3 Ripọtì

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}

Akọwa Nkọwa

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 $^{3}$

Gụọ akwụkwọ nkuzi na Stoichiometry And Chemical Reactions (WAEC)

Stoichiometry And Chemical Reactions

Wo Idahun

Ajụjụ 4 Ripọtì

The hybridization in the compound $C H_{3} - C H_{2} - C \equiv H$ is

sp

^{3}

and sp

sp

^{2}

sp

^{3}

and sp

^{2}

Akọwa Nkọwa

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

Wo Idahun

Ajụjụ 5 Ripọtì

Which of the following statements about catalyst is false?

biological catalysts are called enzymes

catalyst do not appear in the balanced equation

catalyst reduce the activation energy for a reaction

catalysts do not alter the mechanism of the reaction and never appear in the rate low

Chemical Kinetics And Equilibrium System (Nigeria Only)

Wo Idahun

Ajụjụ 6 Ripọtì

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

Wo Idahun

Ajụjụ 7 Ripọtì

The reaction $2 H_{2} S + S O_{2} \to 3 S + 2 H_{2} O$ 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

Wo Idahun

Ajụjụ 8 Ripọtì

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

Wo Idahun

Ajụjụ 9 Ripọtì

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}}

Akọwa Nkọwa

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

Gụọ akwụkwọ nkuzi na Kinetic Theory Of Matter And Gas Laws (JAMB)

Wo Idahun

Ajụjụ 10 Ripọtì

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

Wo Idahun

Ajụjụ 11 Ripọtì

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

Wo Idahun

Ajụjụ 12 Ripọtì

2-methylprop-1-ene is an isomer of

3-methyl but-1-ene

2-methyl but-1-ene

but-2-ene

pent-2-ene

Wo Idahun

Ajụjụ 13 Ripọtì

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

atomic numbers

metallic character

mass number

relative atomic mass

Wo Idahun

Ajụjụ 14 Ripọtì

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

Calcium

Beryllium

Magnesium

Strontium

Akọwa Nkọwa

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.

Gụọ akwụkwọ nkuzi na Metals And Their Compounds (JAMB)

Gụọ akwụkwọ nkuzi na Organic Compounds (JAMB)

Metals And Their Compounds

Organic Compounds

Wo Idahun

Ajụjụ 15 Ripọtì

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

Wo Idahun

Ajụjụ 16 Ripọtì

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

16.2

17.6

16.0

16.4

Akọwa Nkọwa

R.A.M of Z = $16 (\frac{80}{100}) + 18 (\frac{20}{100})$
= $12.8 + 3.6$
= 16.4

Gụọ akwụkwọ nkuzi na Separation Of Mixtures And Purification Of Chemical Substances (JAMB)

Gụọ akwụkwọ nkuzi na Atomic Structure And Bonding (JAMB)

Separation Of Mixtures And Purification Of Chemical Substances

Wo Idahun

Ajụjụ 17 Ripọtì

A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm $^{3}$ of CO $_{2}$ and 54g of water. The hydrocarbon should be

C

_{6}

H

_{6}

C

_{4}

H

_{10}

C

_{5}

H

_{10}

C

_{4}

H

_{6}

Wo Idahun

Ajụjụ 18 Ripọtì

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

Wo Idahun

Ajụjụ 19 Ripọtì

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

Wo Idahun

Ajụjụ 20 Ripọtì

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}

Wo Idahun

Ajụjụ 21 Ripọtì

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

Wo Idahun

Ajụjụ 22 Ripọtì

Which of the following could not be alkane?

C

_{4}

H

_{10}

C

_{5}

H

_{12}

C

_{7}

H

_{14}

C

_{8}

H

_{18}

Wo Idahun

Ajụjụ 23 Ripọtì

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

Wo Idahun

Ajụjụ 24 Ripọtì

The IUPAC name for CH $_{3}$ CH $_{2}$ COOCH $_{2}$ CH $_{3}$ is

methylpropanoate

ethylethanoate

ethylpropanoate

methylethanoate

Wo Idahun

Ajụjụ 25 Ripọtì

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

Wo Idahun

Ajụjụ 26 Ripọtì

X is a substance which liberates CO $_{2}$ on treatment with concentrated H $_{2}$ SO $_{4}$ . A warm solution of X can decolorize acidified KMnO $_{4}$ . X is

HCOOH

NaHCO

_{3}

FeCO

_{3}

H

_{2}

C

_{2}

O

_{4}

Akọwa Nkọwa

It should be noted that for X to liberate CO $_{2}$ , X must be a carbonate or an oxalate. Since X decolorizes KMnO $_{4}$ , X must be an oxalate.
Therefore, X is H $_{2}$ C $_{2}$ O $_{4}$ .

Gụọ akwụkwọ nkuzi na Periodic Chemistry (Ghana Only) (WAEC)

Periodic Chemistry (Ghana Only)

Wo Idahun

Ajụjụ 27 Ripọtì

Which of the following pollutants will lead to the depletion of ozone layer?

chlorofluorocarbon

carbon (ii) oxide

hydrogen sulphide

sulphur (iv) oxide

Environmental Pollution

Wo Idahun

Ajụjụ 28 Ripọtì

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

Wo Idahun

Ajụjụ 29 Ripọtì

Consider the equation below:

Cr $_{2}$ O $_{7}^{2 -}$ + 6Fe $^{2 +}$ + 14H $^{+}$ $\to$ 2Cr $^{3 +}$ + 6Fe $^{3 +}$ + 7H $_{2}$ O.

The oxidation number of chromium changes from

+5 to +3

+6 to +3

-2 to +3

+7 to +3

Akọwa Nkọwa

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

Gụọ akwụkwọ nkuzi na Oxidation And Reduction (JAMB)

Oxidation And Reduction

Wo Idahun

Ajụjụ 30 Ripọtì

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

Wo Idahun

Ajụjụ 31 Ripọtì

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

Wo Idahun

Ajụjụ 32 Ripọtì

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

propylmethanoate

ethylpropanoate

methyl ethanoate

methyl propanoate

Wo Idahun

Ajụjụ 33 Ripọtì

A solution X, on mixing with AgNO $_{3}$ solution gives a white precipitate soluble in aqueous 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)

Wo Idahun

Ajụjụ 34 Ripọtì

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