EIT Chemistry 1 — Questions and Answers
Question 1: What is the molarity of a solution prepared by dissolving 40 g of NaOH (MW = 40 g/mol) in 1 liter of water?
- 0.5 M
- 1.0 M (Correct answer)
- 2.0 M
- 4.0 M
Correct answer: 1.0 M
Molarity = moles/volume = (40 g ÷ 40 g/mol) / 1 L = 1.0 M.
Question 2: What is the pH of a 0.01 M HCl solution?
- 1
- 2 (Correct answer)
- 3
- 4
Correct answer: 2
pH = −log[H⁺] = −log(0.01) = 2.
Question 3: Which of the following is an example of an exothermic reaction?
- Photosynthesis
- Combustion of methane (Correct answer)
- Melting of ice
- Electrolysis of water
Correct answer: Combustion of methane
Combustion of methane releases heat to the surroundings, making it exothermic.
Question 4: The ideal gas law is PV = nRT. What are the SI units of the universal gas constant R?
- J/(mol·K) (Correct answer)
- Pa·m³
- N/m²
- kg·m/s²
Correct answer: J/(mol·K)
R = 8.314 J/(mol·K) in SI units, relating energy to amount of substance and temperature.
Question 5: For a first-order reaction with rate constant k = 0.693 min⁻¹, what is the half-life?
- 0.5 min
- 1.0 min (Correct answer)
- 2.0 min
- 1.44 min
Correct answer: 1.0 min
t½ = ln(2)/k = 0.693/0.693 = 1.0 min for a first-order reaction.
Question 6: How many moles of O₂ are required to completely combust 2 moles of CH₄?
- 2
- 4 (Correct answer)
- 6
- 8
Correct answer: 4
The balanced equation CH₄ + 2O₂ → CO₂ + 2H₂O requires 4 moles of O₂ for 2 moles of CH₄.
EIT Chemistry 1
What is the molarity of a solution prepared by dissolving 40 g of NaOH (MW = 40 g/mol) in 1 liter of water?