Polytechnic Chemistry 1 — Questions and Answers
Question 1: What is the atomic number of carbon?
- 6 (Correct answer)
- 12
- 8
- 4
Correct answer: 6
Carbon has an atomic number of 6, meaning it has 6 protons in its nucleus.
Question 2: What is the pH of a neutral solution at 25°C?
- 7 (Correct answer)
- 0
- 14
- 1
Correct answer: 7
A neutral solution at 25°C has a pH of 7, where hydrogen ion concentration equals hydroxide ion concentration.
Question 3: What type of bond forms between atoms with high electronegativity difference?
- Ionic bond (Correct answer)
- Covalent bond
- Metallic bond
- Hydrogen bond
Correct answer: Ionic bond
Ionic bonds form when one atom donates electrons to another due to a large electronegativity difference (typically > 1.7).
Question 4: What is Avogadro's number?
- 6.022 × 10²³ (Correct answer)
- 6.022 × 10²⁰
- 3.14 × 10²³
- 1.67 × 10⁻²⁷
Correct answer: 6.022 × 10²³
Avogadro's number is 6.022 × 10²³, representing the number of particles in one mole of a substance.
Question 5: Which element has the chemical symbol Na?
- Sodium (Correct answer)
- Nickel
- Nitrogen
- Neon
Correct answer: Sodium
Na is the chemical symbol for sodium, derived from its Latin name 'Natrium'.
Question 6: What is the law of conservation of mass?
- Mass cannot be created or destroyed in a chemical reaction (Correct answer)
- Mass increases during combustion
- Mass of products is always less than reactants
- Mass is conserved only in physical changes
Correct answer: Mass cannot be created or destroyed in a chemical reaction
The law of conservation of mass states that the total mass of reactants equals the total mass of products in a chemical reaction.
Polytechnic Chemistry 1
What is the atomic number of carbon?