Periodic Table and Periodicity AFCAT Questions

AFCAT Chemistry

Periodic Table and Periodicity MCQ Questions


7.
A cation is always smaller than its parent atom because:
A.
Its nuclear charge decreases
B.
It has fewer electrons but the same nuclear charge, increasing effective nuclear pull per electron
C.
It has more electrons than protons
D.
Inner shell electrons are removed
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ANSWER :
B. It has fewer electrons but the same nuclear charge, increasing effective nuclear pull per electron
8.
An anion is larger than its parent atom because:
A.
Addition of electrons increases electron-electron repulsion and decreases effective nuclear charge per electron
B.
Atomic mass increases
C.
Nuclear charge increases on gaining electrons
D.
New shells are always added
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ANSWER :
A. Addition of electrons increases electron-electron repulsion and decreases effective nuclear charge per electron
9.
Among the isoelectronic species O²⁻, F⁻, Na⁺, Mg²⁺, the correct order of increasing ionic radius is:
A.
O²⁻ < F⁻ < Na⁺ < Mg²⁺
B.
Na⁺ < Mg²⁺ < F⁻ < O²⁻
C.
Mg²⁺ < Na⁺ < F⁻ < O²⁻
D.
F⁻ < O²⁻ < Mg²⁺ < Na⁺
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ANSWER :
C. Mg²⁺ < Na⁺ < F⁻ < O²⁻
10.
Which of the following pairs of species is NOT isoelectronic?
A.
Cl⁻ and Ar
B.
Na⁺ and Cl⁻
C.
Na⁺ and Mg²⁺
D.
O²⁻ and F⁻
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ANSWER :
B. Na⁺ and Cl⁻
11.
Among the following, which species has the smallest size: Mg, Mg²⁺, Al, Al³⁺?
A.
Al
B.
Al³⁺
C.
Mg²⁺
D.
Mg
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ANSWER :
B. Al³⁺
12.
The first ionization enthalpy of an element is defined as:
A.
Energy needed to convert a solid element into a gas
B.
Energy required to break a chemical bond
C.
Energy required to remove the most loosely bound electron from an isolated gaseous atom in its ground state
D.
Energy released when an electron is added to a gaseous atom
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ANSWER :
C. Energy required to remove the most loosely bound electron from an isolated gaseous atom in its ground state