In the laboratory preparation of trioxonitrate (V) acid the nitrogen(iv) oxide formed as a by-product is removed by

bubbling air through the acid solution

cooling the acid solution with cold water

bubbling air through the acid solution

JAMB UTME - Chemistry - 2017 | Green Bridge CBT

Question 1 Report

$ {}^{226}_{88}\mathrm{Ra} \rightarrow {}^{x}_{86}\mathrm{Rn} $ + alpha particle

226

220

227

222

Chemical Combination

Atomic Structure And Bonding

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Question 2 Report

Calculate the mass of copper deposited when a current of 0.5 ampere was passed through a solution of copper(II) chloride for 45 minutes in an electrolytic cell. [Cu = 64, F = 96500Cmol-1]

0.300g

0.250g

0.2242g

0.448g

Answer Details

M =

\frac{Molar mass × Quantity of Electricity}{96500 × no of charge}

= $\frac{M m I T}{96500 n}$

Copper II Chloride = CuCl2

CuCl2 → Cu2+ + 2Cl2

Mass of compound deposited = $\frac{Molar mass × Quantity of Electricity}{96500 × no of charge}$

Q = IT

I = 0.5A

T = 45 × 60

T = 2700s

Q = 0.5 × 2700

= 1350c

Molarmass = 64gmol-1

no of charge = + 2

Mass = $\frac{64 \times 1350}{96500 \times 2}$

Mass = 0.448g

Read lesson note on Electrolysis (JAMB)

Electrolysis

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Question 3 Report

For a general equation of the nature xP + yQ ? mR + nS, the expression for the equilibrium constant is

k [P]x [Q]y

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

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

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

Chemical Equilibria

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Question 4 Report

In the laboratory preparation of ethyl ethanoate, the water present in the mixture is removed using a solution of

an hydrous CaCl4

concentrated NaCO4

dilute NaOH

concentrated H4SO4

Acids, Bases And Salts (Ghana Only)

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Question 5 Report

Water for town supply is chlorinate to make it free from

bad colour

bacteria

temporary hardness

permanent hardness

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Question 6 Report

The salt formed from a weak acid and a strong base hydrolyzes in water to form

A saturated solution

an acidic solution

a buffer solution

an alkaline solution

Acids, Bases And Salts (Ghana Only)

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Question 7 Report

Due to the high reactivity of sodium, it is usually stored under

water

mercury

paraffin

phenol

Metals And Their Compounds

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Question 8 Report

X(g) + 3Y(g) ---- 2z(g) H = +ve. if the reaction above takes place at room temperature, the G will be

negative

zero

positive

indeterminate

Answer Details

$\begin{array}{cc} Enthalpy Change [ΔH] & Entropy Change [ΔS] & Gibbs free Energy[ΔG] \\ Positive & Positive & depends on T, may be + or - \\ Negative & Positive & always negative \\ Negative & Negative & depends on T, may be + or - \\ Positive & Negative & always positive \end{array}$

?G= ?H ? T?S.
To determine whether ?G will be positive or negative, the value of ?H(change in enthalpy) and ?S (change in entropy) must be given. Likewise the temperature.

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

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

Kinetic Theory Of Matter And Gas Laws

Chemical Kinetics And Equilibrium Systems (Ghana Only)

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Question 9 Report

The tincture of iodine means iodine dissolved in

ethanol

bromine chloride

chlorine water

water

Acids, Bases And Salts (Ghana Only)

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Question 10 Report

Tin is unaffected by air at ordinary temperature due to its

Low melting point

Weak electropositive character

High boiling point

White lustrous appearance

Chemical Combination

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Question 11 Report

When ΔH is negative, a reaction is said to be

endothermic

exothermic

reversible

ionic

Energy Changes

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Question 12 Report

Ethene is prepared industrially by

Reforming

Polymerization

Distillation

Cracking

Chemical Industry And Environment

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Question 13 Report

A sample of orange juice is found to have a PH of 3.80. What is the concentration of the hydroxide ion in the juice?

1.6

\times

10-4

6.3

\times

10-11

6.3

\times

10-4

1.6

\times

10-11

Acids, Bases And Salts

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Question 14 Report

The reaction of halogens in the presence of sunlight is an example of

oxidation reaction

addition reaction

hydrogenation reaction

substitution reaction

Oxidation And Reduction

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Question 15 Report

The enzyme used in the hydrolysis of starch to dextrin and maltose is

amylase

diastatse

invertase

zymase

Structure Of The Atom (Ghana Only)

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 16 Report

The IUPAC nomenclature of the structure above is

3-methybut-3-ene

2-methylbut-1-ene

2-ethylprop-1-ene

2-methylbut-2-ene

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 17 Report

The densities of two gases, X and Y are 0.5gdm-3 and 2.0gdm-3 respectively. What is the rate of diffusion of X relative to Y?

0.1

0.5

2.0

4.0

Answer Details

The rate of dimension of a gas inversely proportional to the square root of its molecular mass or its density, which is Graham's Law of diffusion of gas.

R ∝ $\frac{1}{\sqrt{M m}}$ or R ∝ $\frac{1}{\sqrt{D}}$

Dx = 0.5gdm-3, Dy = 2gdm-3

R= $\frac{K}{\sqrt{D}}$

R $\sqrt{D}$ = k

R1 $\sqrt{D_{1}}$ = R1 $\sqrt{D_{2}}$

Rx $\sqrt{D_{x}}$ = Ry $\sqrt{D_{y}}$

$\frac{R_{x}}{R_{y}}$ = $\frac{\sqrt{D_{y}}}{\sqrt{D_{x}}}$

= $\frac{\sqrt{2}}{\sqrt{0.5}}$

= 2.0

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

Kinetic Theory Of Matter And Gas Laws

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Question 18 Report

Calculate the amount in moles of a gas which occupies 10.5 dm3 at 6 atm and 30oC [R = 082 atm dm3 K-1 mol-1]

2.536

1.623

4.736

0.394

Answer Details

For an ideal gas PV = nRT

Amount in moles = n

Volume v = 10.5dm3

Pressure P = 6atm

Temperature T = 30°C + 273 = 303k

R, Gas constant = 0.082 atmdm3k-1 mol

Recall from ideal gas equation

pv = nRT

n = $\frac{R V}{R T}$

n = $\frac{6 \times 105}{0.082 \times 303}$

n= 2.536mol

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

Kinetic Theory Of Matter And Gas Laws

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Question 19 Report

The enzyme used in the hydrolysis of starch to dextrin and maltose is

Zymase

Sucrase

Amylase

Lactase

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Question 20 Report

The constituent of air necessary in the rusting process are

O2 and H2O

Ar and CO2

CO2 and H2O

O2 and CO2

Air

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Question 21 Report

An isomer of C5H12 is

2–ethyl butane

butane

2–methyl butane

2–methyl propane

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 22 Report

The general formula of alkanones is

RCHO

R2CO

RCOOH

RCOOR

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 23 Report

Ca(OH)2(s) + 2NH4Cl(g) → CaCl2(s) + 2H2O2(l) + X. In the reaction above X is

NO2

NH3

N2O

H2O

Kinetic Theory Of Matter And Gas Laws

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Question 24 Report

Temporary hard water is formed when rain water containing dissolved carbon(IV) oxide flows over deposits of

CaCO3

Na2CO3

Na2SO4

CaSO4

Oxidation And Reduction

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Question 25 Report

The carbon atoms on ethane are

sp2 hybridized

sp3 hybridized

sp4 hybridized

sp hybridized

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 26 Report

The alkyl group is represented by the general formula

CnH2n

CnH2n − 2

CnH2n + 1

CnH2n + 2

Chemistry Of Carbon Compounds (Nigeria Only)

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Question 27 Report

The ideal gas laws and equations are true for all gases at

low pressures and lower temperatures

low temperatures and high pressures

high pressures and high temperatures

low pressure and high temperatures

Kinetic Theory Of Matter And Gas Laws

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Question 28 Report

If 100cm3 of oxygen pass through a porous plug is 50 seconds, the time taken for the same volume of hydrogen to pass through the same porous plug is? [O = 16, H = 1]

10.0s

12.5s

17.7s

32.0s