Chemistry 2019 Jamb Examination
Chemistry 2019 Jamb Examination
Question 51
What volume of 0.100M sodium trioxonitrate (V) solution contains 5g of solute.
[Na = 23, N = 14, O = 16]
[Na = 23, N = 14, O = 16]
Molar mass of NaNO\(_3\) = 23 + 14 + (16 × 3) = 85 g mol⁻¹.
Moles of solute = 5 ÷ 85 = 0.0588 mol.
Given molarity (M) = 0.100 mol dm⁻³, volume = moles ÷ molarity = 0.0588 ÷ 0.1 = 0.588 dm³ = 0.588 litres.
Therefore, the required volume of solution is 0.588 litres.
Moles of solute = 5 ÷ 85 = 0.0588 mol.
Given molarity (M) = 0.100 mol dm⁻³, volume = moles ÷ molarity = 0.0588 ÷ 0.1 = 0.588 dm³ = 0.588 litres.
Therefore, the required volume of solution is 0.588 litres.
Not clear enough?
Question 52
The two ions responsible for hardness in water are
Hardness in water is mainly caused by the presence of calcium (Ca²⁺) and magnesium (Mg²⁺) ions.
These ions form insoluble salts with soap and are responsible for both temporary and permanent hardness in water.
These ions form insoluble salts with soap and are responsible for both temporary and permanent hardness in water.
Not clear enough?
Question 53
Which of the following could not be alkane?
The general formula for alkanes is C\(_n\)H\(_{2n+2}\).
For C₇H₁₄, hydrogen atoms should be 2n + 2 = 16, but here it is 14.
This shows C₇H₁₄ is not an alkane; it corresponds to an alkene instead.
For C₇H₁₄, hydrogen atoms should be 2n + 2 = 16, but here it is 14.
This shows C₇H₁₄ is not an alkane; it corresponds to an alkene instead.
Not clear enough?
Question 54
The electronic configuration of element Z is 1s² 2s² 2p⁶ 3s² 3p¹. What is the formula of the compound formed between Z and tetraoxosulphate (VI) ion?
The configuration 1s² 2s² 2p⁶ 3s² 3p¹ corresponds to aluminium (Al), which has a valency of +3.
The tetraoxosulphate (VI) ion, SO₄²⁻, has a charge of –2.
To balance charges, 2 Al³⁺ combine with 3 SO₄²⁻ to form Al₂(SO₄)₃.
The tetraoxosulphate (VI) ion, SO₄²⁻, has a charge of –2.
To balance charges, 2 Al³⁺ combine with 3 SO₄²⁻ to form Al₂(SO₄)₃.
Not clear enough?
Question 55
The hybridization in the compound CH₃−CH₂−C≡H is
In CH₃−CH₂−C≡H, the first two carbons are single-bonded and thus sp³-hybridised, while the terminal carbon involved in the triple bond (≡) is sp-hybridised.
Therefore, the hybridizations present are sp³ and sp.
Therefore, the hybridizations present are sp³ and sp.
Not clear enough?
Question 56
The following are isoelectronic ions except
Isoelectronic species have the same number of electrons.
Na⁺ (10e⁻), Mg²⁺ (10e⁻), and O²⁺ (8−2=6e⁻? actually 8−2=6 but incorrect, wait) → Correction: O²⁺ means loss of 2 e⁻, giving 6e⁻.
Hence, only Na⁺ and Mg²⁺ are isoelectronic with Ne (10e⁻), while Si²⁺ has 12 e⁻ and is not isoelectronic.
Na⁺ (10e⁻), Mg²⁺ (10e⁻), and O²⁺ (8−2=6e⁻? actually 8−2=6 but incorrect, wait) → Correction: O²⁺ means loss of 2 e⁻, giving 6e⁻.
Hence, only Na⁺ and Mg²⁺ are isoelectronic with Ne (10e⁻), while Si²⁺ has 12 e⁻ and is not isoelectronic.
Not clear enough?
Question 57
Consider the reaction: A + 2B(g) ⇌ 2C + D(g) (ΔH = +ve)
What will be the effect of decrease in temperature on the reaction?
What will be the effect of decrease in temperature on the reaction?
Since ΔH is positive, the forward reaction is endothermic and favoured by higher temperature.
A decrease in temperature favours the exothermic (reverse) reaction, increasing the rate of the backward reaction.
A decrease in temperature favours the exothermic (reverse) reaction, increasing the rate of the backward reaction.
Not clear enough?
Question 58
A cell shorthand notation can be written as A / A⁺ // B²⁺ / B. The double slash in the notation represents the
In an electrochemical cell notation, the single slash (/) denotes a phase boundary, while the double slash (//) denotes a salt bridge or junction separating the two half-cells.
Therefore, the double slash represents the salt bridge.
Therefore, the double slash represents the salt bridge.
Not clear enough?
Question 59
The shapes of water, ammonia, carbon (IV) oxide and methane are respectively
Water (H₂O) is angular due to two lone pairs on oxygen.
Ammonia (NH₃) is pyramidal due to one lone pair on nitrogen.
Carbon dioxide (CO₂) is linear as it contains two double bonds around carbon.
Methane (CH₄) is tetrahedral with four equal bonds.
Hence, the correct order is angular, pyramidal, linear, and tetrahedral.
Ammonia (NH₃) is pyramidal due to one lone pair on nitrogen.
Carbon dioxide (CO₂) is linear as it contains two double bonds around carbon.
Methane (CH₄) is tetrahedral with four equal bonds.
Hence, the correct order is angular, pyramidal, linear, and tetrahedral.
Not clear enough?
Question 60
Which quantum number divides shells into orbitals?
The azimuthal (or angular momentum) quantum number, denoted by \( l \), determines the subshells or orbitals (s, p, d, f) within a given principal shell.
It defines the shape of the orbital and divides shells into different orbitals.
It defines the shape of the orbital and divides shells into different orbitals.
Not clear enough?
You might like
This question is based on George Orwell's *Nineteen Eighty-Four*. The Ministry of Truth is concerned with
Find all real number x which satisfy the inequality \(\frac{1}{3}\) (x + 1) - 1 > \(\frac{1}{5}\)(x + 4)
I. Jet-propelled aircraft. II Rocket propulsion
III The recoil of a gun. IV A person walking
Which of the above is based on Newton’s third law of motion?
Drilling line does not tend to wear uniformly over its length. The most severe kind of wear occurs at which two kinds of points?
the word in capital letters has the emphatic stress.
Choose the option to which the given sentence relates.
The teacher wants MY pen.
Which of these will not appear in the preparation of a control account?
I. Bad debts
II. Discounts
III. Returns
IV. Provision for bad debts