Q. Which of the following reactions can be used to convert an alkyne to an alkene?
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A.
Hydrogenation
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B.
Halogenation
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C.
Hydrohalogenation
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D.
Dehydrohalogenation
Solution
Hydrogenation of an alkyne will add hydrogen across the triple bond, converting it to an alkene.
Correct Answer: A — Hydrogenation
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Q. Which of the following reactions can be used to prepare alkynes?
-
A.
Hydrogenation of alkenes
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B.
Dehydrohalogenation of alkyl halides
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C.
Oxidation of alkanes
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D.
Hydrolysis of alkynes
Solution
Alkynes can be prepared by the dehydrohalogenation of alkyl halides.
Correct Answer: B — Dehydrohalogenation of alkyl halides
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Q. Which of the following reactions can be used to prepare carboxylic acids?
-
A.
Hydrolysis of esters
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B.
Reduction of ketones
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C.
Oxidation of alcohols
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D.
All of the above
Solution
Carboxylic acids can be prepared by the hydrolysis of esters.
Correct Answer: A — Hydrolysis of esters
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Q. Which of the following reactions has a negative enthalpy change?
-
A.
Dissolving NaCl in water
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B.
Photosynthesis
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C.
Respiration
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D.
Melting of ice
Solution
Respiration is an exothermic reaction that releases energy, resulting in a negative enthalpy change.
Correct Answer: C — Respiration
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Q. Which of the following reactions has a positive ΔG at standard conditions?
-
A.
Combustion of glucose
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B.
Formation of water from hydrogen and oxygen
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C.
Dissolution of salt in water
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D.
Decomposition of hydrogen peroxide
Solution
The decomposition of hydrogen peroxide is non-spontaneous under standard conditions, resulting in a positive ΔG.
Correct Answer: D — Decomposition of hydrogen peroxide
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Q. Which of the following reactions has a positive ΔH and a positive ΔS?
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A.
Combustion of fuels
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B.
Dissolution of salts
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C.
Sublimation of dry ice
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D.
Formation of water from hydrogen and oxygen
Solution
Sublimation of dry ice (solid CO2 to gas) has a positive ΔH (endothermic) and a positive ΔS (increase in disorder).
Correct Answer: C — Sublimation of dry ice
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Q. Which of the following reactions has the highest enthalpy change?
-
A.
Dissolving NaCl in water
-
B.
Combustion of propane
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C.
Formation of NH3 from N2 and H2
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D.
Sublimation of dry ice
Solution
The combustion of propane releases a large amount of energy, resulting in the highest enthalpy change among the options.
Correct Answer: B — Combustion of propane
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Q. Which of the following reactions is a redox reaction?
-
A.
H2 + Cl2 → 2HCl
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B.
NaOH + HCl → NaCl + H2O
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C.
CaCO3 → CaO + CO2
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D.
C6H12O6 + 6O2 → 6CO2 + 6H2O
Solution
The combustion of glucose is a redox reaction where glucose is oxidized.
Correct Answer: D — C6H12O6 + 6O2 → 6CO2 + 6H2O
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Q. Which of the following reactions is characteristic of alkanes?
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A.
Electrophilic substitution
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B.
Nucleophilic substitution
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C.
Free radical substitution
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D.
Addition reaction
Solution
Alkanes undergo free radical substitution reactions, especially in the presence of halogens.
Correct Answer: C — Free radical substitution
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Q. Which of the following reactions is characteristic of alkenes?
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A.
Electrophilic addition
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B.
Nucleophilic substitution
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C.
Free radical substitution
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D.
Elimination
Solution
Alkenes undergo electrophilic addition reactions due to the presence of a double bond.
Correct Answer: A — Electrophilic addition
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Q. Which of the following reactions is characteristic of aromatic compounds?
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A.
Addition reaction
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B.
Substitution reaction
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C.
Elimination reaction
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D.
Redox reaction
Solution
Aromatic compounds typically undergo electrophilic substitution reactions rather than addition reactions due to their stable aromaticity.
Correct Answer: B — Substitution reaction
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Q. Which of the following reactions is expected to have a positive change in entropy?
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A.
N2(g) + 3H2(g) → 2NH3(g)
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B.
C(s) + O2(g) → CO2(g)
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C.
2H2O(l) → 2H2(g) + O2(g)
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D.
CaCO3(s) → CaO(s) + CO2(g)
Solution
The decomposition of liquid water into gaseous hydrogen and oxygen increases the number of gas molecules, leading to a positive change in entropy.
Correct Answer: C — 2H2O(l) → 2H2(g) + O2(g)
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Q. Which of the following reactions is likely to have a negative ΔG?
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A.
Combustion of hydrocarbons.
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B.
Formation of ice from water at 0°C.
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C.
Dissolution of salt in water.
-
D.
Decomposition of hydrogen peroxide.
Solution
The combustion of hydrocarbons is highly exothermic and typically has a negative ΔG, indicating spontaneity.
Correct Answer: A — Combustion of hydrocarbons.
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Q. Which of the following reactions is not typical for alkenes?
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A.
Addition of H2
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B.
Addition of HCl
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C.
Elimination of H2O
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D.
Substitution reaction
Solution
Alkenes typically undergo addition reactions rather than substitution reactions.
Correct Answer: D — Substitution reaction
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Q. Which of the following reactions is spontaneous at all temperatures?
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A.
ΔH < 0 and ΔS < 0
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B.
ΔH > 0 and ΔS > 0
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C.
ΔH < 0 and ΔS > 0
-
D.
ΔH > 0 and ΔS < 0
Solution
A reaction with ΔH < 0 and ΔS > 0 is spontaneous at all temperatures because it results in a negative ΔG.
Correct Answer: C — ΔH < 0 and ΔS > 0
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Q. Which of the following reactions will have a negative ΔG at high temperatures?
-
A.
Exothermic reactions with negative ΔS
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B.
Endothermic reactions with positive ΔS
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C.
Exothermic reactions with positive ΔS
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D.
Endothermic reactions with negative ΔS
Solution
Endothermic reactions with positive ΔS can have a negative ΔG at high temperatures due to the TΔS term becoming significant.
Correct Answer: B — Endothermic reactions with positive ΔS
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Q. Which of the following represents a physical change?
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A.
Burning wood
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B.
Dissolving sugar in water
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C.
Rusting of iron
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D.
Cooking an egg
Solution
Dissolving sugar in water is a physical change as it does not alter the chemical composition of sugar.
Correct Answer: B — Dissolving sugar in water
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Q. Which of the following represents an endothermic reaction?
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A.
Combustion of gasoline
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B.
Dissolving ammonium nitrate in water
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C.
Respiration
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D.
Rusting of iron
Solution
Dissolving ammonium nitrate in water absorbs heat, making it an endothermic reaction.
Correct Answer: B — Dissolving ammonium nitrate in water
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Q. Which of the following represents the correct relationship between moles and mass?
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A.
Moles = Mass / Molar Mass
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B.
Mass = Moles x Molar Mass
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C.
Molar Mass = Mass / Moles
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D.
All of the above
Solution
All the given relationships are correct and represent the conversion between moles, mass, and molar mass.
Correct Answer: D — All of the above
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Q. Which of the following represents the correct relationship between moles, mass, and molar mass?
-
A.
moles = mass × molar mass
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B.
mass = moles × molar mass
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C.
molar mass = mass / moles
-
D.
mass = moles / molar mass
Solution
The correct relationship is mass = moles × molar mass.
Correct Answer: B — mass = moles × molar mass
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Q. Which of the following represents the enthalpy change for a reaction at constant pressure?
Solution
The enthalpy change for a reaction at constant pressure is represented by ΔH.
Correct Answer: B — ΔH
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Q. Which of the following represents the number of particles in one mole of a substance?
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A.
6.022 x 10^23
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B.
3.14 x 10^22
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C.
1.6 x 10^19
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D.
9.11 x 10^28
Solution
Avogadro's number is 6.022 x 10^23, which represents the number of particles in one mole.
Correct Answer: A — 6.022 x 10^23
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Q. Which of the following s-block elements has the highest melting point?
-
A.
Lithium
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B.
Sodium
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C.
Potassium
-
D.
Rubidium
Solution
Lithium has the highest melting point among the alkali metals due to its small size and strong metallic bonding.
Correct Answer: A — Lithium
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Q. Which of the following s-block elements is a liquid at room temperature?
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A.
Lithium
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B.
Sodium
-
C.
Potassium
-
D.
Mercury
Solution
Mercury is a liquid at room temperature, but it is not an s-block element; however, among the options, it is the only liquid.
Correct Answer: D — Mercury
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Q. Which of the following s-block elements is essential for human health?
-
A.
Sodium
-
B.
Calcium
-
C.
Potassium
-
D.
All of the above
Solution
Sodium, calcium, and potassium are all essential s-block elements for human health, playing vital roles in various physiological processes.
Correct Answer: D — All of the above
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Q. Which of the following s-block elements is known for forming a protective oxide layer?
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A.
Sodium
-
B.
Potassium
-
C.
Calcium
-
D.
Magnesium
Solution
Magnesium forms a protective oxide layer that prevents further oxidation.
Correct Answer: D — Magnesium
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Q. Which of the following s-block elements is known for its use in batteries?
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A.
Lithium
-
B.
Sodium
-
C.
Potassium
-
D.
Calcium
Solution
Lithium is widely used in batteries, especially in rechargeable lithium-ion batteries.
Correct Answer: A — Lithium
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Q. Which of the following s-block elements is least reactive?
-
A.
Lithium
-
B.
Sodium
-
C.
Potassium
-
D.
Rubidium
Solution
Lithium is the least reactive among the alkali metals.
Correct Answer: A — Lithium
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Q. Which of the following s-block elements is most reactive?
-
A.
Lithium
-
B.
Sodium
-
C.
Potassium
-
D.
Rubidium
Solution
Rubidium is the most reactive among the s-block elements listed.
Correct Answer: D — Rubidium
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Q. Which of the following s-block elements is the least reactive?
-
A.
Lithium
-
B.
Sodium
-
C.
Potassium
-
D.
Rubidium
Solution
Lithium is the least reactive among the alkali metals.
Correct Answer: A — Lithium
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