IB Chemistry 4 — Questions and Answers
Question 1: What is the molar mass of glucose (C₆H₁₂O₆) in g/mol?
- 160
- 180 (Correct answer)
- 172
- 196
Correct answer: 180
Molar mass = 6(12) + 12(1) + 6(16) = 72 + 12 + 96 = 180 g/mol.
Question 2: Which of the following statements about catalysts is correct?
- Catalysts are consumed in the reaction
- Catalysts increase the activation energy
- Catalysts provide an alternative pathway with lower activation energy (Correct answer)
- Catalysts shift the equilibrium position
Correct answer: Catalysts provide an alternative pathway with lower activation energy
Catalysts work by providing an alternative reaction pathway with a lower activation energy, increasing reaction rate without being consumed.
Question 3: In acid-base chemistry, what does the term 'amphoteric' mean?
- Substance that only acts as an acid
- Substance that only acts as a base
- Substance that can act as both an acid and a base (Correct answer)
- Substance that does not react with acids or bases
Correct answer: Substance that can act as both an acid and a base
An amphoteric substance can donate or accept protons depending on the reaction conditions; water (H₂O) is a common example.
Question 4: What is the product when an alcohol undergoes dehydration?
- Alkane
- Alkene (Correct answer)
- Carboxylic acid
- Ester
Correct answer: Alkene
Dehydration of an alcohol removes water (H₂O) and produces an alkene via an elimination reaction.
Question 5: Which law states that the pressure of a gas is inversely proportional to its volume at constant temperature?
- Charles's Law
- Avogadro's Law
- Boyle's Law (Correct answer)
- Gay-Lussac's Law
Correct answer: Boyle's Law
Boyle's Law states that P₁V₁ = P₂V₂ at constant temperature, showing an inverse relationship between pressure and volume.
Question 6: Which of the following molecules exhibits hydrogen bonding?
- CH₄
- CCl₄
- NH₃ (Correct answer)
- H₂S
Correct answer: NH₃
NH₃ exhibits hydrogen bonding because nitrogen is highly electronegative and has lone pairs that can accept hydrogen bonds from N–H groups.
Question 7: What is the electron configuration of a neutral iron (Fe) atom (atomic number 26)?
- [Ar] 3d⁸
- [Ar] 4s² 3d⁶ (Correct answer)
- [Ar] 4s¹ 3d⁷
- [Kr] 4s² 3d⁶
Correct answer: [Ar] 4s² 3d⁶
Iron's configuration is [Ar] 4s² 3d⁶, with the 4s subshell filling before 3d in the ground state.
IB Chemistry 4
What is the molar mass of glucose (C₆H₁₂O₆) in g/mol?