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Question 1: Who is credited with inventing the pH scale in 1909?
- Søren Sørensen
- Svante Arrhenius
- Gilbert N. Lewis
- Johannes Brønsted
Answer: A. Søren Sørensen
Explanation: Danish chemist Søren Sørensen developed the pH scale in 1909 while working at the Carlsberg Laboratory in Copenhagen to monitor the influence of hydrogen ion concentration on enzymes and proteins.
Question 2: Which scientist proposed that acids increase hydrogen ion concentration in 1884?
- Gilbert N. Lewis
- Søren Sørensen
- Johannes Brønsted
- Svante Arrhenius
Answer: D. Svante Arrhenius
Explanation: Svante Arrhenius proposed in 1884 that acids increase the concentration of hydrogen ions in aqueous solutions, while bases increase hydroxide ion concentration, earning him the 1903 Nobel Prize in Chemistry.
Question 3: In the Brønsted-Lowry theory, what does an acid act as?
- Proton donor
- Proton acceptor
- Electron-pair acceptor
- Electron-pair donor
Answer: A. Proton donor
Explanation: The Brønsted-Lowry theory, developed independently in 1923, defines an acid as a proton donor and a base as a proton acceptor, providing a clear model for acid-base reactions.
Question 4: What is a Lewis acid defined as?
- Proton acceptor
- Electron-pair donor
- Proton donor
- Electron-pair acceptor
Answer: D. Electron-pair acceptor
Explanation: Gilbert N. Lewis proposed in 1923 that a Lewis acid is an electron-pair acceptor and a Lewis base is an electron-pair donor, which is a more general definition than Brønsted-Lowry.
Question 5: Why was the pH scale originally developed at the Carlsberg Laboratory?
- To test soil acidity
- To analyze ocean water
- To monitor beer brewing
- To study human blood
Answer: C. To monitor beer brewing
Explanation: Søren Sørensen originally developed the pH scale to monitor the influence of hydrogen ion concentration on enzymes and proteins during the beer brewing process at the Carlsberg Laboratory in Copenhagen.
Question 6: What term describes a substance that can act as either an acid or a base?
- Neutral
- Conjugate
- Dissociative
- Amphoteric
Answer: D. Amphoteric
Explanation: Water is considered amphoteric because it can act as either a Brønsted-Lowry acid or a Brønsted-Lowry base depending on the reaction, demonstrating the versatility of water in chemical processes.
Question 7: What does a conjugate acid-base pair consist of?
- Two neutral compounds
- Two species differing by one electron
- Two identical molecules
- Two species differing by one proton
Answer: D. Two species differing by one proton
Explanation: In the Brønsted-Lowry model, a conjugate acid-base pair consists of two species that differ by exactly one proton, which is a fundamental concept for understanding acid-base equilibrium in chemistry.
Question 8: Which theory does not require the presence of hydrogen ions?
- Sørensen theory
- Brønsted-Lowry theory
- Arrhenius theory
- Lewis theory
Answer: D. Lewis theory
Explanation: The Lewis definition of acids and bases is more general than the Brønsted-Lowry definition because it does not require the presence of a solvent or hydrogen ions for the reaction.
Question 9: What is the typical range of the pH scale?
- 0 to 14
- 1 to 12
- 0 to 7
- 1 to 10
Answer: A. 0 to 14
Explanation: The pH scale is defined as the negative logarithm of the hydrogen ion activity in a solution, and it typically ranges from 0 to 14 in most common laboratory applications.
Question 10: For what work did Svante Arrhenius receive a Nobel Prize in 1903?
- Theory of electrolytic dissociation
- Development of the Lewis acid theory
- Discovery of the pH scale
- Study of enzyme kinetics
Answer: A. Theory of electrolytic dissociation
Explanation: Svante Arrhenius received the 1903 Nobel Prize in Chemistry for his theory of electrolytic dissociation, which explains how substances dissociate into ions in water, forming the basis for his acid-base theory.