Chemistry, 2018, JAMB Exam, Exam, Paper 1 | Objectives

Paper Info

Year :

2018

Title :

Chemistry

Exam :

JAMB Exam

Paper 1 | Objectives

81 - 87 of 87 Questions

#	Question	Ans
81.	H\(_2\) S\(_{(g)}\) + Cl\(_{2(g)}\) → 2HCl\(_{(g)}\) + S\(_{(g)}\) In the reaction above, the substance that is reduced is A. H\(_2\)S B. S C. HCl D. Cl\(_2\) Show Content Detailed Solution H \(_2\) S + Cl \(_2\) → 2HCl + S Please note: substance oxidized or reduced are always the reactants. So, one can easily cross out the two products. Reduction is 1. Addition of hydrogen 2. Removal of Oxygen 3. Addition of Electron Oxidation is 1. Removal of hydrogen 2. Addition of hydrogen 3. Removal of Electron From the question we can see that H was added to Cl in the product, thereby making hydrogen to be removed from S in the reactant hence S is oxidized as a result of the removal of hydrogen and Cl \(_2\) has been reduced due to addition of hydrogen. Cl \(_2\) is reduced There is an explanation video	D
82.	Which of the compounds is composed of Al, Si, O and H? A. Epson salt B. Limestone C. Clay D. Urea Show Content Detailed Solution Between the five main minerals found in clay, kaolinite is the most common. Kaolinite holds the chemical composition Al\(_{2}\) Si\(_{2}\)O\(_{5}\)(OH)\(_{4}\) and is an aluminum silicate material with a low “shrink-swell” capacity. It is a soft, white mineral but is often colored orange or red by iron oxide found in the soil. There is an explanation video available below.	C
83.	When large hydrocarbon molecules are heated at high temperature in the presence of a catalyst to give smaller molecules, the process is known as A. disintegration B. polymerization C. cracking D. degradation Show Content Detailed Solution Cracking is the breakdown of a large alkane into smaller, more useful alkenes. Simply put, hydrocarbon cracking is the process of breaking a long-chain of hydrocarbons into short ones. This process might require high temperatures and high pressure. There is an explanation video available below.	C
84.	In the removal of water hardness, permutit is regenerated with a strong solution of A. NaOH B. Na\(_3\)SO\(_4\) C. Na\(_3\)CO\(_3\) D. NaCl
85.	A sample of hard water contains some calcium sulphate and calcium hydrogen carbonate. The total hardness may therefore be removed by A. boiling the water B. adding excess calcium hydroxide C. adding a calculated amount of calcium hydroxide D. adding sodium carbonate Show Content Detailed Solution its D because when sodium carbonate reacts with calcium hydrogentrioxocarbonate it gives sodium hydrogentrioxocarbonate and calcium trioxocarbonate. However, when it react with calcium sulphate, calcium carbonate and sodium tetraoxosulphate is formed There is an explanation video available below.	D
86.	Which of the following separation techniques can be employed in obtaining solvent from its solution? A. Evaporation B. Distillation C. Filtration D. Precipitation Show Content Detailed Solution Distillation is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation. There is an explanation video available below.	B
87.	In the upper atmosphere, the ultra-violet light breaks off a free chlorine atom from chlorofluorocarbon molecule. The effect of this is that the free chlorine atom will A. be very reactive and will attack ozone B. be non-reactive and will not attack ozone C. not change the level of ozone in the atmosphere D. increase the level of ozone in the atmosphere Show Content Detailed Solution CFCs (Chlorofluorocarbons) have a lifetime in the atmosphere of about 20 to 100 years, and consequently one free chlorine atom from a CFC molecule can do a lot of damage, destroying ozone molecules for a long time There is an explanation video available below.	A

81.	H\(_2\) S\(_{(g)}\) + Cl\(_{2(g)}\) → 2HCl\(_{(g)}\) + S\(_{(g)}\) In the reaction above, the substance that is reduced is A. H\(_2\)S B. S C. HCl D. Cl\(_2\) Show Content Detailed Solution H \(_2\) S + Cl \(_2\) → 2HCl + S Please note: substance oxidized or reduced are always the reactants. So, one can easily cross out the two products. Reduction is 1. Addition of hydrogen 2. Removal of Oxygen 3. Addition of Electron Oxidation is 1. Removal of hydrogen 2. Addition of hydrogen 3. Removal of Electron From the question we can see that H was added to Cl in the product, thereby making hydrogen to be removed from S in the reactant hence S is oxidized as a result of the removal of hydrogen and Cl \(_2\) has been reduced due to addition of hydrogen. Cl \(_2\) is reduced There is an explanation video	D
82.	Which of the compounds is composed of Al, Si, O and H? A. Epson salt B. Limestone C. Clay D. Urea Show Content Detailed Solution Between the five main minerals found in clay, kaolinite is the most common. Kaolinite holds the chemical composition Al\(_{2}\) Si\(_{2}\)O\(_{5}\)(OH)\(_{4}\) and is an aluminum silicate material with a low “shrink-swell” capacity. It is a soft, white mineral but is often colored orange or red by iron oxide found in the soil. There is an explanation video available below.	C
83.	When large hydrocarbon molecules are heated at high temperature in the presence of a catalyst to give smaller molecules, the process is known as A. disintegration B. polymerization C. cracking D. degradation Show Content Detailed Solution Cracking is the breakdown of a large alkane into smaller, more useful alkenes. Simply put, hydrocarbon cracking is the process of breaking a long-chain of hydrocarbons into short ones. This process might require high temperatures and high pressure. There is an explanation video available below.	C
84.	In the removal of water hardness, permutit is regenerated with a strong solution of A. NaOH B. Na\(_3\)SO\(_4\) C. Na\(_3\)CO\(_3\) D. NaCl

85.	A sample of hard water contains some calcium sulphate and calcium hydrogen carbonate. The total hardness may therefore be removed by A. boiling the water B. adding excess calcium hydroxide C. adding a calculated amount of calcium hydroxide D. adding sodium carbonate Show Content Detailed Solution its D because when sodium carbonate reacts with calcium hydrogentrioxocarbonate it gives sodium hydrogentrioxocarbonate and calcium trioxocarbonate. However, when it react with calcium sulphate, calcium carbonate and sodium tetraoxosulphate is formed There is an explanation video available below.	D
86.	Which of the following separation techniques can be employed in obtaining solvent from its solution? A. Evaporation B. Distillation C. Filtration D. Precipitation Show Content Detailed Solution Distillation is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation. There is an explanation video available below.	B
87.	In the upper atmosphere, the ultra-violet light breaks off a free chlorine atom from chlorofluorocarbon molecule. The effect of this is that the free chlorine atom will A. be very reactive and will attack ozone B. be non-reactive and will not attack ozone C. not change the level of ozone in the atmosphere D. increase the level of ozone in the atmosphere Show Content Detailed Solution CFCs (Chlorofluorocarbons) have a lifetime in the atmosphere of about 20 to 100 years, and consequently one free chlorine atom from a CFC molecule can do a lot of damage, destroying ozone molecules for a long time There is an explanation video available below.	A

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