The modern periodic law was proposed by: MCQ with Answer and Explanation

Question
The modern periodic law was proposed by:
A. John Newlands
B. Lothar Meyer
C. Dmitri Mendeleev
D. Henry Moseley
Answer: Option D
Solution (By JKExamLibrary)
Dmitri Mendeleev proposed the periodic law based on atomic mass. However, anomalies arose. In 1913, Henry Moseley discovered that the atomic number (number of protons) is the fundamental property. He proposed the modern periodic law: the properties of elements are periodic functions of their atomic numbers.
This question belongs to: Science chemistry

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Practice More chemistry Questions

Question #1
Soap is formed by the alkaline hydrolysis of fats and oils. This reaction is called:
A. Emulsification
B. Esterification
C. Hydrogenation
D. Saponification
Discuss

Correct Answer: Option D

Explanation:
Saponification is the hydrolysis of triglycerides (fats/oils) with NaOH or KOH to produce glycerol and the sodium or potassium salts of long-chain fatty acids, which are soaps. Esterification is the formation of esters from acid and alcohol. Emulsification is the dispersion of one liquid in another. Hydrogenation is addition of H₂. Hard soaps use NaOH, soft soaps use KOH. Soaps clean by micelle formation.
This question belongs to: Science chemistry
Question #2
Rutherford's alpha-scattering experiment led to the discovery of the:
A. Proton
B. Neutron
C. Electron
D. Nucleus
Discuss

Correct Answer: Option D

Explanation:
In 1911, Ernest Rutherford conducted the gold foil experiment, firing alpha particles at a thin gold sheet. While most passed through, a few were deflected at large angles, and some bounced back. This led him to conclude that the atom's positive charge and most of its mass are concentrated in a tiny, dense central core called the nucleus.
This question belongs to: Science chemistry
Question #3
The metal that is extracted by the electrolytic reduction of its fused salt is:
A. Copper
B. Zinc
C. Iron
D. Sodium
Discuss

Correct Answer: Option D

Explanation:
Highly reactive metals (K, Na, Ca, Mg, Al) are extracted by electrolysis of their fused (molten) salts because chemical reducing agents cannot reduce their ores. For sodium, Down's process: electrolysis of molten NaCl with CaCl₂ to lower melting point. Iron is extracted by smelting (blast furnace). Copper and zinc can be extracted by reduction with coke or electrolytic refining of impure metal.
This question belongs to: Science chemistry
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