Classification of Elements and Periodicity in Properties NDA Questions

NDA Chemistry

Classification of Elements and Periodicity in Properties MCQ Questions


7.
The Modern Periodic Law was proposed by Henry Moseley (1913) based on:
A.
X-ray spectra of elements — he found that the square root of the frequency of characteristic X-rays was directly proportional to the atomic number Z, establishing atomic number as the more fundamental property
B.
Measurement of atomic masses using mass spectrometry
C.
Optical spectra of elements studied using spectroscopes
D.
The discovery of neutrons in the nucleus by James Chadwick
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ANSWER :
A. X-ray spectra of elements — he found that the square root of the frequency of characteristic X-rays was directly proportional to the atomic number Z, establishing atomic number as the more fundamental property
8.
The Modern Periodic Law states that:
A.
Metallic character is the only property that shows periodicity
B.
The physical and chemical properties of elements are a periodic function of their ATOMIC NUMBERS
C.
Properties of elements depend on their atomic masses exclusively
D.
Elements with the same number of neutrons have identical chemical properties
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ANSWER :
B. The physical and chemical properties of elements are a periodic function of their ATOMIC NUMBERS
9.
The modern periodic table (long form) consists of:
A.
6 periods and 18 groups
B.
7 periods and 8 groups
C.
7 periods (horizontal rows) and 18 groups (vertical columns)
D.
8 periods and 16 groups
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ANSWER :
C. 7 periods (horizontal rows) and 18 groups (vertical columns)
10.
The number of elements in periods 1, 2, 3, 4, 5, 6 and 7 respectively are:
A.
8, 8, 8, 18, 18, 32, 32
B.
2, 2, 8, 8, 18, 18, 32
C.
2, 8, 8, 18, 32, 32, 18
D.
2, 8, 8, 18, 18, 32, 32
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ANSWER :
D. 2, 8, 8, 18, 18, 32, 32
11.
Why does the 6th period of the periodic table contain 32 elements?
A.
32 is derived from the formula 2n for n = 16
B.
The 6th period involves filling of 6s (2e), 4f (14e), 5d (10e) and 6p (6e) orbitals: total 2+14+10+6 = 32 electrons (and hence 32 elements)
C.
The 6th period has 32 elements due to the filling of only 6s and 6p orbitals
D.
The 6th period has 32 elements because it has 6 sub-shells each holding 5–6 electrons
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ANSWER :
B. The 6th period involves filling of 6s (2e), 4f (14e), 5d (10e) and 6p (6e) orbitals: total 2+14+10+6 = 32 electrons (and hence 32 elements)
12.
In the modern periodic table, a 'PERIOD' represents:
A.
A group of elements that have the same atomic mass
B.
A block of elements with the same number of valence electrons
C.
A horizontal row in the periodic table; all elements in a period have the same number of electron shells (same value of principal quantum number n for the outermost shell)
D.
A vertical column containing elements with similar chemical properties
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ANSWER :
C. A horizontal row in the periodic table; all elements in a period have the same number of electron shells (same value of principal quantum number n for the outermost shell)