Free CART Chemical Reactions Questions and Answers — Questions and Answers
Question 1: Which of the following is a balanced equation for the combustion of methane (CH₄)?
- CH₄ + O₂ → CO₂ + H₂O
- CH₄ + 2O₂ → CO₂ + 2H₂O (Correct answer)
- CH₄ + O₂ → CO + H₂O
- CH₄ + 3O₂ → 2CO₂ + 2H₂O
Correct answer: CH₄ + 2O₂ → CO₂ + 2H₂O
To balance the combustion of methane (CH₄), the number of atoms for each element must be equal on both sides of the equation. One carbon atom on the left requires one CO₂ on the right. Four hydrogen atoms on the left require two H₂O on the right (2*2=4). This then results in four oxygen atoms on the right (2 from CO₂ + 2 from 2H₂O), which means two O₂ molecules are needed on the left (2*2=4).
Question 2: What type of reaction is represented by the equation: 2H₂ + O₂ → 2H₂O?
- Decomposition reaction
- Single displacement reaction
- Synthesis reaction (Correct answer)
- Double displacement reaction
Correct answer: Synthesis reaction
A synthesis reaction, also known as a combination reaction, is characterized by two or more simple reactants combining to form a more complex product. In the given equation, hydrogen and oxygen gases combine to form water, fitting this definition perfectly.
Question 3: In a chemical reaction, the substances that are present at the beginning and undergo change are called:
- Reactants (Correct answer)
- Products
- Catalysts
- Inhibitors
Correct answer: Reactants
In a chemical reaction, the substances that are present at the beginning and undergo a chemical change are called reactants. These starting materials are consumed during the reaction to form new substances, which are known as products.
Question 4: Which of the following represents a double displacement reaction?
- AB + CD → AD + CB (Correct answer)
- AB → A + B
- A + BC → AC + B
- A + B → AB
Correct answer: AB + CD → AD + CB
A double displacement reaction involves the exchange of ions between two compounds, typically in an aqueous solution. The cations of the two reactants effectively switch places to form two new compounds, following the general form AB + CD → AD + CB.
Question 5: What is the law that states that mass is neither created nor destroyed in a chemical reaction?
- Law of Definite Proportions
- Law of Conservation of Mass (Correct answer)
- Law of Multiple Proportions
- Law of Conservation of Energy
Correct answer: Law of Conservation of Mass
The Law of Conservation of Mass states that in any closed system, mass is neither created nor destroyed during a chemical reaction. This fundamental law means that the total mass of the reactants must equal the total mass of the products.
Free CART Chemical Reactions Questions and Answers
Which of the following is a balanced equation for the combustion of methane (CH₄)?