Chemistry, 2019, JAMB Exam, Exam, Paper 1 | Objectives

Paper Info

Year :

2019

Title :

Chemistry

Exam :

JAMB Exam

Paper 1 | Objectives

71 - 80 of 80 Questions

#	Question	Ans
71.	If the cost of electricity required to discharge 10g of an ion X\(^{3+}\) is N20.00, how much would it cost to discharge 6g of ion Y\(^{2+}\)?[1 faraday = 96,500C, atomic masses are X = 27, Y = 24] A. N10.00 B. N6.00 C. N20.00 D. N9.00 Show Content Detailed Solution X\(^{3+}\) + 3e\(^-\) \(\to\) X 3F = 27g xF = 10g \(\frac{x}{3} = \frac{10}{27} \implies x = \frac{10}{9} F\) \(\frac{10}{9}\)F \(\equiv\) N20.00 1F is equivalent to x \(\frac{1}{\frac{10}{9}} = \frac{x}{20}\) \(\frac{9}{10} = \frac{x}{20} \implies x = N18.00\) 1F is equivalent to N18.00. Y\(^{2+}\) + 2e\(^-\) \(\to\) Y 2F = 24g xF = 6g x = \(\frac{6 \times 2}{24} = \frac{1}{2} F\) 1F = N18.00 \(\frac{1}{2}\)F = \(\frac{1}{2} \times N18.00\) = N9.00 There is an explanation video available below.	D
72.	The cost of discharging 6.0g of a divalent metal, X from its salt is ₦12.00. What is the cost of discharging 9.0g of a trivalent metal, Y from its salt under the same condition? [X = 63, Y = 27, 1F = 96,500C] A. N12.00 B. N27.00 C. N63.00 D. N95.00 Show Content Detailed Solution For X: X\(^{2+}\) + 2e\(^-\) \(\to\) X 2F = 63g xF = 6g x = \(\frac{6 \times 2}{63} = \frac{4}{21} F\) \(\frac{4}{21}\)F = N12.00 1F = \(\frac{12}{\frac{4}{21}}\) = N63.00 1F is equivalent to N63.00. For Y: Y\(^{3+}\) + 3e\(^-\) \(\to\) Y 3F = 27g xF = 9g x = \(\frac{3 \times 9}{27}\) = 1F 1F = N63.00 There is an explanation video available below.	C
73.	How many alkoxyalkanes can be obtained from the molecular formula C\(_4\)H\(_{10}\)O? A. 4 B. 2 C. 1 D. 3 Show Content Detailed Solution ethoxlethane methoxylpropane propoxylmethane There is an explanation video available below.	D
74.	The reaction \(2H_2 S + SO_2 \to 3S + 2H_2 O\) is A. not a redox reaction because there is no oxidant in the reaction B. not a redox reaction because there is no reductant in the reaction C. a redox reaction in which H\(_2\)S is the oxidant and SO\(_2\) is the reductant D. a redox reaction in which SO\(_2\) is the oxidant and H\(_2\)S is the reductant Show Content Detailed Solution There is an explanation video available below.	D
75.	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 A. Al\(^{3+}\), Cl\(^-\) B. Hg\(^+\), SO\(_4 ^{2-}\) C. Pb\(^{2+}\), Cl\(^-\) D. Ag\(^+\), SO\(_4 ^{2-}\) Show Content Detailed Solution There is an explanation video available below.	C
76.	How many electrons will be found in the nucleus of an atom with mass number 23 and 17 neutrons? A. none B. 6 C. 7 D. 8 Show Content Detailed Solution Electrons are found in the orbit of the atom. They revolve around the nucleus. There's no electron found in the nucleus of an atom. There is an explanation video available below.	A
77.	An element Z contains 80% of \(^{16} _8\)Z and 20% of \(^{18} _8\)Z. Its relative atomic mass is A. 16.2 B. 17.6 C. 16.0 D. 16.4 Show Content Detailed Solution R.A.M of Z = \(16(\frac{80}{100}) + 18(\frac{20}{100})\) = \(12.8 + 3.6\) = 16.4 There is an explanation video available below.	D
78.	When the end alkyl groups of ethyl ethanoate are interchanged, the compound formed is A. propylmethanoate B. ethylpropanoate C. methyl ethanoate D. methyl propanoate Show Content Detailed Solution The structural formula for ethyl ethanoate is After interchanging, we have Which is the structural formula for methyl propanoate. There is an explanation video available below.	D
79.	The part of the total energy of a system that accounts for the useful work done in a system is known as A. Enthalpy change B. None of the above C. Gibb's free energy D. Entropy Show Content Detailed Solution Gibb's free energy is the fraction of the total energy of a system that accounts for how much useful work can be done in a system. There is an explanation video available below.	C
80.	Which of the following factors will speed up the rate of evolution of carbon (iv) oxide in the reaction below? 2HCl + CaCO\(_3\) → CaCl\(_2\) + H\(_2\)O + CO\(_2\) A. Increasing the concentration of the acid B. Increasing the surface area of CaCO\(_3\) C. A and B D. Reducing the concentration of the acid Show Content Detailed Solution The following factors increase a reaction rate - Increase in concentration of reactants - Increase in temperature - Addition of catalyst - Increase in the surface area of reactant(s) There is an explanation video available below.	C

71.	If the cost of electricity required to discharge 10g of an ion X\(^{3+}\) is N20.00, how much would it cost to discharge 6g of ion Y\(^{2+}\)?[1 faraday = 96,500C, atomic masses are X = 27, Y = 24] A. N10.00 B. N6.00 C. N20.00 D. N9.00 Show Content Detailed Solution X\(^{3+}\) + 3e\(^-\) \(\to\) X 3F = 27g xF = 10g \(\frac{x}{3} = \frac{10}{27} \implies x = \frac{10}{9} F\) \(\frac{10}{9}\)F \(\equiv\) N20.00 1F is equivalent to x \(\frac{1}{\frac{10}{9}} = \frac{x}{20}\) \(\frac{9}{10} = \frac{x}{20} \implies x = N18.00\) 1F is equivalent to N18.00. Y\(^{2+}\) + 2e\(^-\) \(\to\) Y 2F = 24g xF = 6g x = \(\frac{6 \times 2}{24} = \frac{1}{2} F\) 1F = N18.00 \(\frac{1}{2}\)F = \(\frac{1}{2} \times N18.00\) = N9.00 There is an explanation video available below.	D
72.	The cost of discharging 6.0g of a divalent metal, X from its salt is ₦12.00. What is the cost of discharging 9.0g of a trivalent metal, Y from its salt under the same condition? [X = 63, Y = 27, 1F = 96,500C] A. N12.00 B. N27.00 C. N63.00 D. N95.00 Show Content Detailed Solution For X: X\(^{2+}\) + 2e\(^-\) \(\to\) X 2F = 63g xF = 6g x = \(\frac{6 \times 2}{63} = \frac{4}{21} F\) \(\frac{4}{21}\)F = N12.00 1F = \(\frac{12}{\frac{4}{21}}\) = N63.00 1F is equivalent to N63.00. For Y: Y\(^{3+}\) + 3e\(^-\) \(\to\) Y 3F = 27g xF = 9g x = \(\frac{3 \times 9}{27}\) = 1F 1F = N63.00 There is an explanation video available below.	C
73.	How many alkoxyalkanes can be obtained from the molecular formula C\(_4\)H\(_{10}\)O? A. 4 B. 2 C. 1 D. 3 Show Content Detailed Solution ethoxlethane methoxylpropane propoxylmethane There is an explanation video available below.	D
74.	The reaction \(2H_2 S + SO_2 \to 3S + 2H_2 O\) is A. not a redox reaction because there is no oxidant in the reaction B. not a redox reaction because there is no reductant in the reaction C. a redox reaction in which H\(_2\)S is the oxidant and SO\(_2\) is the reductant D. a redox reaction in which SO\(_2\) is the oxidant and H\(_2\)S is the reductant Show Content Detailed Solution There is an explanation video available below.	D
75.	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 A. Al\(^{3+}\), Cl\(^-\) B. Hg\(^+\), SO\(_4 ^{2-}\) C. Pb\(^{2+}\), Cl\(^-\) D. Ag\(^+\), SO\(_4 ^{2-}\) Show Content Detailed Solution There is an explanation video available below.	C

76.	How many electrons will be found in the nucleus of an atom with mass number 23 and 17 neutrons? A. none B. 6 C. 7 D. 8 Show Content Detailed Solution Electrons are found in the orbit of the atom. They revolve around the nucleus. There's no electron found in the nucleus of an atom. There is an explanation video available below.	A
77.	An element Z contains 80% of \(^{16} _8\)Z and 20% of \(^{18} _8\)Z. Its relative atomic mass is A. 16.2 B. 17.6 C. 16.0 D. 16.4 Show Content Detailed Solution R.A.M of Z = \(16(\frac{80}{100}) + 18(\frac{20}{100})\) = \(12.8 + 3.6\) = 16.4 There is an explanation video available below.	D
78.	When the end alkyl groups of ethyl ethanoate are interchanged, the compound formed is A. propylmethanoate B. ethylpropanoate C. methyl ethanoate D. methyl propanoate Show Content Detailed Solution The structural formula for ethyl ethanoate is After interchanging, we have Which is the structural formula for methyl propanoate. There is an explanation video available below.	D
79.	The part of the total energy of a system that accounts for the useful work done in a system is known as A. Enthalpy change B. None of the above C. Gibb's free energy D. Entropy Show Content Detailed Solution Gibb's free energy is the fraction of the total energy of a system that accounts for how much useful work can be done in a system. There is an explanation video available below.	C
80.	Which of the following factors will speed up the rate of evolution of carbon (iv) oxide in the reaction below? 2HCl + CaCO\(_3\) → CaCl\(_2\) + H\(_2\)O + CO\(_2\) A. Increasing the concentration of the acid B. Increasing the surface area of CaCO\(_3\) C. A and B D. Reducing the concentration of the acid Show Content Detailed Solution The following factors increase a reaction rate - Increase in concentration of reactants - Increase in temperature - Addition of catalyst - Increase in the surface area of reactant(s) There is an explanation video available below.	C

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