In the modern periodic table, elements in the same group have the same: MCQ with Answer and Explanation

In the modern periodic table, elements in the same group have the same:
A. Number of valence electrons
B. Number of isotopes
C. Atomic mass
D. Number of electron shells
Answer: Option A
Solution (By JKExamLibrary)
Elements in the same group (vertical column) have the same number of valence electrons, resulting in similar chemical properties. For example, all Group 1 elements have 1 valence electron (ns¹). The number of shells increases down the group. Atomic mass varies. This similarity was the basis for Mendeleev's grouping. Modern table uses atomic number for ordering.

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Practice More chemistry Questions

Question #1
Which of the following is an example of catalytic poisoning?
A. Addition of phosphoric acid to slow down H2O2 decomposition.
B. Addition of molybdenum to iron in Haber's process.
C. Arsenic ruining the activity of finely divided iron in Haber's process.
D. Platinum increasing the rate of combustion of hydrogen.

Correct Answer: Option C


Explanation:
Catalytic poisoning occurs when a substance (a catalytic poison) binds strongly to the active sites of a catalyst, blocking reactants from adsorbing and thereby destroying or reducing its catalytic activity. Arsenic acts as a poison for the iron catalyst used in the Haber process for ammonia synthesis.

This question belongs to: Science chemistry
Question #2
Carbon forms bonds by:
A. Gaining 4 electrons
B. Ionic transfer
C. Losing 4 electrons
D. Sharing 4 electrons

Correct Answer: Option D


Explanation:
Carbon has 4 valence electrons; it forms four covalent bonds by sharing electrons to achieve octet. It does not form ionic bonds easily due to high ionization energy and electron affinity.

This question belongs to: Science chemistry
Question #3
The simplest alkene is:
A. Propyne
B. Ethene
C. Ethane
D. Methane

Correct Answer: Option B


Explanation:
Alkenes contain at least one carbon-carbon double bond. The simplest alkene is ethene (C₂H₄). Methane is an alkane; ethane is an alkane; propyne is an alkyne. General formula for alkenes: CₙH₂ₙ.

This question belongs to: Science chemistry