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Chemistry
UTME / JAMB 2019
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
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?
A
25cm\(^3\)
B
10cm\(^3\)
C
20cm\(^3\)
D
50cm\(^3\)
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
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)
\(\frac{1.25 \times 10}{0.5 \times V_B} = \frac{1}{2}\)
\(\frac{12.5}{0.5V_B} = \frac{1}{2}\)
25 = 0.5V\(_B\)
VB = 50.0 cm\(^3\)
Source: Myschool Past Questions Archive (Record #55791)
Chemistry
UTME / JAMB 2019
Atomic Structure, Orbitals & Nuclear Chemistry
Sulphur exists in six forms in the solid state. This property is known as
A
Isomerism
B
Allotropy
C
Isotopy
D
Isomorphism
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #55794)
Chemistry
UTME / JAMB 2019
Stoichiometry, Mole Concept & Volumetric Analysis
In the reaction:
M + N → P
\DeltaH = +Q kJ
Which of the following would increase the concentration of the product?
A
Adding a suitable catalyst
B
Increasing the concentration of P
C
Increasing the temperature
D
Decreasing the temperature
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #55795)
Chemistry
UTME / JAMB 2019
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
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]
A
C\(_3\)H\(_6\)O\(_3\)
B
C\(_6\)H\(_6\)O\(_3\)
C
C\(_6\)H\(_{12}\)O\(_6\)
D
CH\(_2\)O
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
C → 40/12 ≈ 3
H → 6.7/1 ≈ 6
O → 53.3/16 ≈ 3
dividing through with the lowest value, 3
C\(_1\)H\(_2\)O\(_1\)
[C\(_1\)H\(_2\)O\(_1\)]n = 180
[12 + 2 + 16]m = 180
30n = 180
n = 6
:C\(_6\)H\(_12\)O\(_6\)
Source: Myschool Past Questions Archive (Record #55799)
Chemistry
UTME / JAMB 2019
Organic Chemistry I: Hydrocarbons & Crude Oil
The IUPAC nomenclature of the compound
H\(_3\)C - CH(CH\(_3\)) - CH(CH\(_3\)) - CH\(_2\) - CH\(_3\)
A
3,4- dimethylhexane
B
2,3- dimethyl pentane
C
2- ethyl hexane
D
2,3- dimethylhexane
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #55807)
Chemistry
UTME / JAMB 2019
Organic Chemistry I: Hydrocarbons & Crude Oil
Solution
Which of the following gases contains the least number of atoms at s.t.p?
A
1 mole of butane
B
4 moles of chlorine
C
3 moles of ozone
D
7 moles of argon
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
4 moles of chlorine gas = 4Cl\(_2\) = 8 atoms of chlorine
3 moles of ozone = 3O\(_3\) = 9 atoms of oxygen
1 mole of butane = C\(_4\)H\(_{10}\)
7 mole of argon = 7Ar = 7 atoms of argon
Argon is a monoatomic noble gas with the least number of atoms.
Source: Myschool Past Questions Archive (Record #55809)
Chemistry
UTME / JAMB 2019
Electrolysis & Electrochemical Cells
Solution
What mass of magnesium would be obtained by passing a current of 2 amperes for 2 hours 30 mins, through molten magnesium chloride?
[1 faraday = 96500C, Mg = 24]
A
1.12g
B
4.48g
C
1.80g
D
2.24g
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Given Data:
Time (T) = 2hrs 30mins
where 2hrs =120mins
2hrs & 30mins = (120 + 30)mins = 150mins
150mins to Seconds = 150 x60 = 9,000s
Q = I x T
2 x 9,000 =18,000
where mg has valency of +2
So 2 x 96500 will discharge 24g of mg
and 18,000 will discharge xg of mg
2 x 96500 =24
18,000 =x
x = \(\frac{24 \times 18,000}{2 x 96500}\)
≈ 2.24g
Source: Myschool Past Questions Archive (Record #55813)
Chemistry
UTME / JAMB 2019
Stoichiometry, Mole Concept & Volumetric Analysis
Which important nitrogen-containing compound is produced in Haber's process?
A
NH\(_3\)
B
NO\(_2\)
C
NO
D
HNO\(_3\)
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #55817)
Chemistry
UTME / JAMB 2019
Periodic Table & Periodicity
Elements in the periodic table are arranged in the order of their
A
atomic numbers
B
metallic character
C
mass number
D
relative atomic mass
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #55819)
Chemistry
UTME / JAMB 2019
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
What volume of 0.100M sodium trioxonitrate (V) solution contains 5g of solute ?
[Na = 23, N = 14, O = 16]
A
1.7 litres
B
0.420 litres
C
0.588 litres
D
2.35 litres
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Given:
V = ? , C = 0.100M, m = 5g
Molar mass, M of NaNO\(_3\) = 23 + 14 + (16 X 3) = 85 g/mol
Number of moles, n = \(\frac{mass}{Molar Mass}\)
= \(\frac{5}{85}\)
n = 0.0588 mole
Recall that n = \(\frac{CV}{1000}\)
n = CV (looking through the options, no need including the 1000 since the answer was left in Litres)
V = \(\frac{n}{C}\)
V = \(\frac{0.0588}{0.100}\)
V = 0.588 Litres
Source: Myschool Past Questions Archive (Record #55820)
Chemistry
UTME / JAMB 2019
Water, Solutions & Solubility
The two ions responsible for hardness in water are
A
Ca\(^{2+}\) and / or Mg\(^{2+}\)
B
K\(^+\) and / or Mg\(^{2+}\)
C
Ca\(^{2+}\) and / or Li\(^+\)
D
Ca\(^{2+}\) and / or Na\(^+\)
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #55822)
Chemistry
UTME / JAMB 2019
Organic Chemistry I: Hydrocarbons & Crude Oil
Which of the following could not be alkane?
A
C\(_4\)H\(_{10}\)
B
C\(_5\)H\(_{12}\)
C
C\(_7\)H\(_{14}\)
D
C\(_8\)H\(_{18}\)
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #55824)
Chemistry
UTME / JAMB 2019
Atomic Structure, Orbitals & Nuclear Chemistry
Solution
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.
A
Z\(_3\)(SO\(_4\))\(_2\)
B
ZSO\(_4\)
C
Z\(_2\) SO\(_4\)
D
Z\(_2\)(SO\(_4\))\(_3\)
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Z = 1s\(^2\) 2s\(^2\) 2p\(^6\) 3s\(^2\) 3p\(^1\)
\(\therefore\) We have Z\(^{3+}\) and SO\(_4 ^{2-}\)
The reaction : Z\(^{3+}\) + SO\(_4 ^{2-}\) \(\to\) Z\(_2\)(SO\(_4\))\(_3\).
Source: Myschool Past Questions Archive (Record #55998)
Chemistry
UTME / JAMB 2019
Chemical Bonding & Intermolecular Forces
Solution
The hybridization in the compound \(CH_3 - CH_2 - C \equiv H\) is
A
sp\(^3\) and sp
B
sp
C
sp\(^2\)
D
sp\(^3\) and sp\(^2\)
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
The hybridization in a and b is sp\(^3\) hybridization while in c and d is sp hybridization.
Source: Myschool Past Questions Archive (Record #55999)
Chemistry
UTME / JAMB 2019
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
The following are isoelectronic ions except
A
Na\(^+\)
B
Mg\(^{2+}\)
C
Si\(^{2+}\)
D
O\(^{2+}\)
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
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
\(\implies\) Si\(^{2+}\) is not isoelectronic with the rest.
Source: Myschool Past Questions Archive (Record #56000)