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

The modern periodic law was proposed by:
A. John Newlands
B. Dmitri Mendeleev
C. Henry Moseley
D. Lothar Meyer
Answer: Option C
Solution (By JKSSB Mock Tests)
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.

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Practice More chemistry Questions

Question #1
Methanol is toxic. Ingestion of methanol leads to:
A. Kidney failure
B. Blindness or death
C. Lung cancer
D. Liver cirrhosis

Correct Answer: Option B


Explanation:
Methanol is metabolized in the body to formaldehyde and formic acid, which are highly toxic and can damage the optic nerve, causing permanent blindness or even death if ingested in significant amounts. Ethanol is used as an antidote because it competitively inhibits methanol metabolism by alcohol dehydrogenase. Methanol is used as industrial solvent and in illegal liquor (hooch) sometimes resulting in mass poisoning.

This question belongs to: Science chemistry
Question #2
The metal used in the manufacture of stainless steel is:
A. Zinc
B. Copper
C. Chromium
D. Lead

Correct Answer: Option C


Explanation:
Stainless steel is an iron alloy containing at least 10.5% chromium, which provides corrosion resistance by forming a passive chromium oxide layer. Nickel and molybdenum may also be added. Copper and zinc are components of brass. Lead is used in batteries and solder. Chromium is essential for 'stainless' property.

This question belongs to: Science chemistry
Question #3
Which of the following will cause an increase in the rate of evaporation of a liquid?
A. Increase in surface area
B. Decrease in temperature
C. Increase in humidity
D. Decrease in wind speed

Correct Answer: Option A


Explanation:
Evaporation increases with an increase in surface area, temperature, and wind speed, and decreases with an increase in humidity. A larger surface area allows more liquid molecules to be exposed to the air, enabling them to escape into the vapor phase more quickly, thus increasing the rate of evaporation.

This question belongs to: Science chemistry