MCQ 141
Which of the following represents a combination reaction?
A) 2H₂ + O₂ → 2H₂O
B) 2NaCl → 2Na + Cl₂
C) H₂O → H₂ + O₂
D) CH₄ + O₂ → CO₂ + H₂O
Answer: A) 2H₂ + O₂ → 2H₂O.
Explanation: A combination reaction occurs when two or more reactants combine to form a single product.
MCQ 142
What is the primary characteristic of a chemical bond?
A) It is a physical interaction.
B) It involves the sharing or transfer of electrons.
C) It only occurs in solids.
D) It cannot be broken.
Answer: B) It involves the sharing or transfer of electrons.
Explanation: Chemical bonds are formed by the sharing (covalent bonds) or transfer (ionic bonds) of electrons between atoms.
MCQ 143
Which of the following is NOT a characteristic of acids?
A) Sour taste
B) pH less than 7
C) Slippery feel
D) Turns blue litmus red
Answer: C) Slippery feel.
Explanation: A slippery feel is characteristic of bases, not acids.
MCQ 144
What type of reaction is represented by the equation: CaCO₃ → CaO + CO₂?
A) Synthesis
B) Decomposition
C) Single replacement
D) Double replacement
Answer: B) Decomposition.
Explanation: This reaction shows a single compound breaking down into two or more products, characteristic of decomposition reactions.
MCQ 145
Which of the following statements is true according to Dalton’s atomic theory?
A) Atoms can be created and destroyed.
B) All atoms of a given element are identical in mass and properties.
C) Atoms can be divided into smaller particles.
D) Different elements can combine in any ratio.
Answer: B) All atoms of a given element are identical in mass and properties.
Explanation: Dalton’s atomic theory states that atoms of the same element are identical in mass and properties.
MCQ 146
What is the main product when glucose undergoes complete combustion?
A) Water and carbon dioxide
B) Water and carbon monoxide
C) Ethanol and carbon dioxide
D) Hydrogen and oxygen
Answer: A) Water and carbon dioxide.
Explanation: The complete combustion of glucose produces water (H₂O) and carbon dioxide (CO₂).
MCQ 147
Which of the following represents an oxidation reaction?
A) 2H₂ + O₂ → 2H₂O
B) C + O₂ → CO₂
C) Zn + Cu²⁺ → Zn²⁺ + Cu
D) Fe²⁺ → Fe³⁺
Answer: D) Fe²⁺ → Fe³⁺.
Explanation: Oxidation is the loss of electrons; here, iron is losing an electron and increasing its oxidation state.
MCQ 148
Which gas is typically produced when a carbonate reacts with an acid?
A) Oxygen
B) Carbon dioxide
C) Hydrogen
D) Nitrogen
Answer: B) Carbon dioxide.
Explanation: The reaction of carbonates with acids produces carbon dioxide gas as one of the products.
MCQ 149
Which law states that when gases combine or are produced in a chemical reaction, they do so in simple whole number ratios by volume?
A) Dalton’s Law
B) Avogadro’s Law
C) Boyle’s Law
D) Charles’s Law
Answer: B) Avogadro’s Law.
Explanation: Avogadro’s Law states that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.
MCQ 150
What does a balanced chemical equation indicate?
A) The reaction is complete.
B) The relative amounts of reactants and products involved.
C) The type of bonds formed.
D) The energy changes involved.
Answer: B) The relative amounts of reactants and products involved.
Explanation: A balanced equation shows the ratio of reactants to products, reflecting the conservation of mass.
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