NSMQ PAST QUESTION PDF; CHEMISTRY (01)

NSMQ PAST QUESTION PDF; CHEMISTRY (01)

What is the most likely mode of decay for each of the following nuclides?

• Carbon – 15

Ans: Beta decay

• Uranium – 238 (atomic number 92)

Answer: alpha decay

• Nitrogen – 12

Ans: positron emission (or electron capture)

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Identify the following species found on the Periodic Table given the information below:

1. Mass number 33; neutron number 18; number of electrons 18

Ans: P^3–

2. Mass number 55; neutron number 30; number of electrons 22

Answer: Mn³⁺

3. Mass number 66; neutron number 36; number of electrons 28

Ans: Zn²

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Give the name of the major product formed in each of the following reactions

1. The Reaction of benzene with chlorine in the presence of aluminum chloride

Ans: chlorobenzene

2. The reaction of 2-methylpropane with a limited amount of chlorine gas

Answer: 2-chloro-2-methyl propane

3. The reaction of butanoic acid and methylamine

Ans: N-methyl butanamide

During the production of pure iron, Fe₂O₃ reacts with carbon monoxide, CO, according to the reaction: Fe₂O₃ + 3 CO → 2Fe + 3CO₂

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1. How many moles of phosphorus is present in 14.2 g of P₄O₁₀? Take the atomic mass (g/mol) of phosphorus and oxygen as 31 and 16, respectively.

Ans: n(P) = 0.20 mol

n(P₄O₁₀) = 14.2/284 = 0.050 mol; P = 4 × 0.05 = 0.20 mol

2. Determine the sum of the stoichiometric coefficients of all reactants and products present in a balanced equation of the reaction: C₃H₈ + O₂ → CO₂ + H₂O

Answer: 13

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

3. How many unpaired electrons are present in the molecule NO?

Ans: one (1)

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Give the name of the major product formed from the reaction of HBr with each of the following:

1. 1-pentene

Ans: 2-bromopentane

2. 2-methyl-2-butene

Answer: 2-bromo-2-methylbutane

3. Cyclohexene

Ans: Bromo cyclohexane (or 1-bromo cyclohexane)

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1. What mass of oxygen is needed to produce 90 g of water given that an excess amount of hydrogen reacts? Take the atomic mass (g/mol) of H and O as 1.0 and 16 respectively.

Ans: 80 g

Mol of H₂O = 90/18 = 5.0 mol.

n O₂ = 5.0/2 = 2.5 mol                 Hence mass = 2.5 × 32 = 80 g

2. Determine the mass of Na₂CO₃ needed to produce 0.150 mol of carbon dioxide gas in a thermal decomposition reaction. Take the atomic mass (g/mol) of Na, C, and O as 23.0, 12.0 and 16.0 respectively.

Ans: 15.9 g

Molar mas of Na₂CO₃ = 106    since mole ratio is 1:1, mass = 106 × 0.150 = 15.9 g

3. Based on a reaction with solid carbon, determine the mass of oxygen needed to produce 16.8 g of carbon monoxide given that, oxygen is limited. Take the atomic mass (g/mol) of C and O as 12 and 16 respectively.

Ans: 9.6 g

Mol of CO = 16.8/28 = 0.60 mol           mol of O₂ = 0.60/2 = 0.30 mol

Mass of O₂ = 9.6 g

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1. Given Avogadro’s number as 6.0 × 10²³, how many atoms of oxygen are present in 4.0 moles of SO₃?

Ans: 7.2 × 10²⁴

Number of atoms = 6.0 × 10²³  × 4 mol × 3 O atoms = 7.2 × 10²⁴

2. Determine the sum of the stoichiometric coefficients of all reactants and products present in a balanced equation of the reaction: C₆H₈ + O₂ → CO₂ + H₂O

Answer: 19

C₆H₈ + 😯₂ →6CO₂ + 4H₂O

3. What is the maximum number of hydrogen bonds formed by a water molecule in ice?

Ans: four (4)

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Indicate the values of all quantum numbers permissible for the following orbitals

1. 4p

Ans: n = 4, l = 1, ml = -1, 0, +1

2. 3d

Answer: n = 3, l = 2, ml = -2, -1, 0, +1, +2

3. 5s

Ans: n = 5, l = 0, ml = 0

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State and explain the effect of each of the following actions on the equilibrium of the reaction

1. An increase in pressure

Ans: Equilibrium will shift toward the formation of more product (right/forward)

An increase in pressure will favour the side with fewer moles of gas. Mole of reactants is 3 and moles of product is 2, hence pressure will favour formation of product/forward reaction

2. An increase in temperature

Ans: Equilibrium will shift toward the formation of more reactants (left/backwards)

Since reaction is exothermic, increase in temperature will favour the formation of reactants

3. A decrease in the amount of oxygen gas

Ans: Equilibrium will shift toward the formation of more reactants (left/backwards)

More SO₃ will breakdown to form O₂ in other to negative the effect of the reduced concentration of O₂.

Download NSMQ Past Question; Chemistry (01) 

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