Chemistry Notes

Fbise ssc result

Concept of octane number was introduced by

Chemical kinetics

1. What does the rate of a chemical reaction measure?
a) The change in concentration of reactants or products over time
b) The total energy change during the reaction
c) The equilibrium constant of the reaction
d) The activation energy of the reaction

Answer: a) The change in concentration of reactants or products over time

2. Which factor does NOT affect the rate of a chemical reaction?
a) Temperature
b) Concentration of reactants
c) Presence of a catalyst
d) Equilibrium constant

Answer: d) Equilibrium constant

3. What is the role of a catalyst in a chemical reaction?
a) It increases the equilibrium constant of the reaction
b) It decreases the activation energy of the reaction
c) It changes the stoichiometry of the reaction
d) It increases the final concentration of products

Answer: b) It decreases the activation energy of the reaction

4. What is the order of a reaction if the rate is independent of the concentration of the reactants?
a) Zero order
b) First order
c) Second order
d) Third order

Answer: a) Zero order

5. What does the Arrhenius equation describe?
a) The relationship between temperature and equilibrium constant
b) The relationship between temperature and reaction rate
c) The relationship between concentration and reaction rate
d) The relationship between activation energy and equilibrium constant

Answer: b) The relationship between temperature and reaction rate

6. Which of the following is true about the half-life of a first-order reaction?
a) It depends on the initial concentration of the reactant
b) It is inversely proportional to the rate constant
c) It is independent of the initial concentration of the reactant
d) It increases as the reaction progresses

Answer: c) It is independent of the initial concentration of the reactant

7. What is the unit of the rate constant for a second-order reaction?
a) s⁻¹
b) mol L⁻¹ s⁻¹
c) L mol⁻¹ s⁻¹
d) mol² L⁻² s⁻¹

Answer: c) L mol⁻¹ s⁻¹

8. What is the activation energy of a reaction?
a) The energy released during the reaction
b) The energy required to break the bonds of the reactants
c) The minimum energy required for reactants to form products
d) The energy difference between reactants and products

Answer: c) The minimum energy required for reactants to form products

9. Which of the following statements about reaction mechanisms is true?
a) The slowest step in the mechanism is called the rate-determining step
b) The overall reaction rate is determined by the fastest step
c) Intermediate species appear in the overall balanced equation
d) The reaction mechanism is always the same as the stoichiometric equation

Answer: a) The slowest step in the mechanism is called the rate-determining step

10. What happens to the rate of a reaction if the temperature is increased?
a) The rate decreases because the activation energy increases
b) The rate increases because more molecules have energy greater than the activation energy
c) The rate remains unchanged because the equilibrium constant is unaffected
d) The rate decreases because the reaction becomes exothermic

Answer: b) The rate increases because more molecules have energy greater than the activation energy.

Lipids

1. Which of the following is a primary function of lipids in biological systems?**
A. Catalyzing metabolic reactions
B. Storing genetic information
C. Providing structural integrity to cell membranes
D. Facilitating muscle contraction

Answer: C. Providing structural integrity to cell membranes
Explanation: Lipids, particularly phospholipids, are a major component of cell membranes, providing structural integrity and forming a barrier between the cell and its environment.

2. Which type of lipid is primarily responsible for energy storage in animals?
A. Phospholipids
B. Steroids
C. Triglycerides
D. Waxes

Answer: C. Triglycerides
Explanation: Triglycerides are the main form of stored energy in animals, as they contain long hydrocarbon chains that can be broken down to release energy.

3. What is the key structural difference between saturated and unsaturated fatty acids?
A. Saturated fatty acids have double bonds, while unsaturated fatty acids do not.
B. Unsaturated fatty acids have double bonds, while saturated fatty acids do not.
C. Saturated fatty acids contain a glycerol backbone, while unsaturated fatty acids do not.
D. Unsaturated fatty acids are always liquid at room temperature, while saturated fatty acids are solid.

Answer: B. Unsaturated fatty acids have double bonds, while saturated fatty acids do not.
Explanation: Unsaturated fatty acids contain one or more double bonds in their hydrocarbon chains, whereas saturated fatty acids have no double bonds.

4. Which lipid is a precursor for the synthesis of steroid hormones such as cortisol and estrogen?
A. Cholesterol
B. Phosphatidylcholine
C. Sphingomyelin
D. Triacylglycerol

Answer: A. Cholesterol
Explanation: Cholesterol is a key precursor for the synthesis of steroid hormones, including cortisol, estrogen, and testosterone.

5. What is the role of lipoproteins in lipid metabolism?
A. They break down lipids into fatty acids and glycerol.
B. They transport lipids through the bloodstream.
C. They store lipids in adipose tissue.
D. They synthesize lipids in the liver.

Answer:B. They transport lipids through the bloodstream.
Explanation: Lipoproteins, such as LDL and HDL, are complexes of lipids and proteins that transport lipids (e.g., cholesterol and triglycerides) through the bloodstream to various tissue

Electrochemistry

1. What is the primary function of a salt bridge in an electrochemical cell?
A) To provide a path for electron flow
B) To maintain electrical neutrality in the half-cells
C) To increase the voltage of the cell
D) To act as a catalyst for the reaction

Answer: B

2. In a galvanic cell, where does oxidation occur?
A) At the cathode
B) At the anode
C) In the salt bridge
D) In the external circuit

Answer: B

3. Which of the following is true about the standard hydrogen electrode (SHE)?
A) It has a fixed potential of 1.0 V
B) It is used as a reference electrode with a potential of 0.0 V
C) It is always the cathode in an electrochemical cell
D) It is made of platinum and gold

Answer: B

4. What is the relationship between the standard Gibbs free energy change (ΔG°) and the standard cell potential (E°)?
A) ΔG° = -nFE°
B) ΔG° = nFE°
C) ΔG° = E°/nF
D) ΔG° = -E°/nF

Answer: A)

5. Which of the following statements is true for an electrolytic cell?
A) It converts chemical energy into electrical energy
B) It requires an external power source to drive a non-spontaneous reaction
C) It always has a positive cell potential
D) It does not involve redox reactions

Answer: B

6. What is the Nernst equation used for?
A) To calculate the standard cell potential
B) To determine the equilibrium constant of a reaction
C) To calculate the cell potential under non-standard conditions
D) To measure the pH of a solution

Answer: C

7. Which of the following factors does NOT affect the conductivity of an electrolyte solution?
A) Temperature
B) Concentration of ions
C) Nature of the solvent
D) Pressure

Answer: D

8. What is the role of a cathode in an electrochemical cell?
A) It undergoes oxidation
B) It undergoes reduction
C) It provides electrons to the external circuit
D) It acts as a salt bridge

Answer: B

9. Which of the following is an example of a secondary battery?
A) Zinc-carbon battery
B) Lithium-ion battery
C) Alkaline battery
D) Lead-acid battery

Answer: D

10. What is the Faraday constant (F) a measure of?
A) The charge on one mole of electrons
B) The voltage of a standard hydrogen electrode
C) The conductivity of an electrolyte solution
D) The Gibbs free energy of a reaction

Answer: A