Thermal decomposition of limestone produces: MCQ with Answer and Explanation

Thermal decomposition of limestone produces:
A. CaO and CO
B. Ca and CO₂
C. CaO and CO₂
D. Ca(OH)₂ and CO₂
Answer: Option C
Solution (By JKExamLibrary)
Limestone is CaCO₃. On strong heating, it decomposes to calcium oxide (quicklime) and carbon dioxide: CaCO₃ → CaO + CO₂. This is a decomposition reaction used in cement and lime manufacturing. CaO is used in building and as a drying agent.

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Practice More chemistry Questions

Question #1
The chemical used as an antacid is:
A. Calcium sulfate
B. Sodium bicarbonate
C. Sodium hydroxide
D. Sodium chloride

Correct Answer: Option B


Explanation:
Sodium bicarbonate (NaHCO₃) neutralizes excess stomach acid (HCl) and provides relief from acidity. It is a mild base. NaOH is too strong and corrosive. NaCl is table salt; CaSO₄ is used in plaster of Paris.

This question belongs to: Science chemistry
Question #2
The modern periodic table is based on the periodic law proposed by:
A. Henry Moseley
B. John Dalton
C. Niels Bohr
D. Dmitri Mendeleev

Correct Answer: Option A


Explanation:
Henry Moseley discovered that the atomic number (number of protons) is the fundamental property of an element, not atomic mass. He proposed the modern periodic law: properties are periodic functions of atomic numbers. Mendeleev's law was based on atomic mass, which had anomalies.

This question belongs to: Science chemistry
Question #3
Which of the following reactions is an example of a Wurtz reaction?
A. CH3Cl + Na -> C2H6 + NaCl
B. CH3Cl + KOH(aq) -> CH3OH + KCl
C. 2CH3Cl + Zn -> C2H6 + ZnCl2
D. CH3Cl + KOH(alc) -> CH4 + KCl

Correct Answer: Option A


Explanation:
The Wurtz reaction involves the reaction of an alkyl halide with sodium metal in dry ether to form a higher alkane. For example, two molecules of methyl chloride react with two sodium atoms to form ethane (C2H6) and sodium chloride. It is primarily used to synthesize symmetrical alkanes with an even number of carbon atoms.

This question belongs to: Science chemistry