ESAT ESAT Chemistry 1 — Questions and Answers
Question 1: What is the molar mass of water (H₂O)?
- 18 g/mol (Correct answer)
- 16 g/mol
- 20 g/mol
- 34 g/mol
Correct answer: 18 g/mol
H₂O: 2(1) + 16 = 18 g/mol, using standard atomic masses.
Question 2: In ESAT Chemistry, what does a higher activation energy indicate?
- Slower reaction rate (Correct answer)
- Faster reaction rate
- Higher product yield
- Exothermic reaction
Correct answer: Slower reaction rate
Higher activation energy means fewer molecules have sufficient energy to react, resulting in a slower rate.
Question 3: What type of bonding involves the sharing of electron pairs between atoms?
- Covalent bonding (Correct answer)
- Ionic bonding
- Metallic bonding
- Hydrogen bonding
Correct answer: Covalent bonding
Covalent bonds are formed by the sharing of one or more electron pairs between atoms.
Question 4: Which of the following is an example of an oxidation reaction?
- Mg → Mg²⁺ + 2e⁻ (Correct answer)
- Fe³⁺ + e⁻ → Fe²⁺
- Cu²⁺ + 2e⁻ → Cu
- Cl₂ + 2e⁻ → 2Cl⁻
Correct answer: Mg → Mg²⁺ + 2e⁻
Oxidation is loss of electrons (OIL RIG); Mg losing 2 electrons to form Mg²⁺ is oxidation.
Question 5: What is the pH of a solution with [H⁺] = 1 × 10⁻³ mol/L?
- 3 (Correct answer)
- 7
- 11
- -3
Correct answer: 3
pH = -log[H⁺] = -log(10⁻³) = 3.
Question 6: How many moles of NaCl are in 117 g? (Molar mass NaCl = 58.5 g/mol)
- 2 mol (Correct answer)
- 1 mol
- 0.5 mol
- 58.5 mol
Correct answer: 2 mol
n = mass / molar mass = 117 / 58.5 = 2 mol.
ESAT ESAT Chemistry 1
What is the molar mass of water (H₂O)?