AS Associate Of Science In Chemistry 2 — Questions and Answers
Question 1: In which type of reaction do two or more substances combine to form a single product?
- Decomposition reaction
- Synthesis (combination) reaction (Correct answer)
- Single-replacement reaction
- Combustion reaction
Correct answer: Synthesis (combination) reaction
A synthesis (combination) reaction occurs when two or more reactants combine to form one product, represented as A + B → AB.
Question 2: What is the name of the model that describes electrons occupying specific energy levels around the nucleus?
- Thomson plum pudding model
- Rutherford nuclear model
- Bohr model (Correct answer)
- Quantum mechanical model
Correct answer: Bohr model
The Bohr model proposes that electrons orbit the nucleus in fixed energy levels (shells) and can jump between levels by absorbing or emitting energy.
Question 3: What is molarity (M) defined as in chemistry?
- Moles of solute per kilogram of solvent
- Grams of solute per liter of solution
- Moles of solute per liter of solution (Correct answer)
- Volume of solute per volume of solvent
Correct answer: Moles of solute per liter of solution
Molarity (M) is the concentration unit defined as the number of moles of solute dissolved per liter of solution.
Question 4: Which element is found in all organic compounds?
- Hydrogen
- Oxygen
- Carbon (Correct answer)
- Nitrogen
Correct answer: Carbon
Carbon is the defining element of organic chemistry; all organic compounds contain carbon atoms, usually bonded to hydrogen.
Question 5: What is the oxidation state of oxygen in most compounds?
- +2
- 0
- −2 (Correct answer)
- −1
Correct answer: −2
Oxygen typically has an oxidation state of −2 in most compounds, except in peroxides (−1) and when bonded to fluorine (+2).
Question 6: What happens to the rate of a chemical reaction when temperature is increased?
- It decreases because molecules move slower
- It remains unchanged
- It increases because more molecules have sufficient activation energy (Correct answer)
- It decreases because activation energy increases
Correct answer: It increases because more molecules have sufficient activation energy
Increasing temperature raises the average kinetic energy of molecules, so a greater fraction of collisions have sufficient energy to overcome the activation energy barrier, increasing reaction rate.
AS Associate Of Science In Chemistry 2
In which type of reaction do two or more substances combine to form a single product?