Elements NDA Questions

NDA Chemistry

Elements MCQ Questions


7.
The most serious anomaly/limitation of Mendeleev's periodic table was:
A.
Placement of elements in wrong order of atomic masses — e.g., Cobalt (58.9) placed before Nickel (58.7) despite higher mass
B.
He listed only 63 elements out of the 118 known today
C.
He did not place hydrogen in the table
D.
He grouped noble gases with halogens
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ANSWER :
A. Placement of elements in wrong order of atomic masses — e.g., Cobalt (58.9) placed before Nickel (58.7) despite higher mass
8.
The Modern Periodic Law, replacing Mendeleev's, was formulated based on Moseley's work (1913) and states:
A.
Properties depend only on the number of neutrons
B.
Properties are a function of atomic masses
C.
Properties repeat after every 8 elements
D.
The properties of elements are a periodic function of their atomic numbers
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ANSWER :
D. The properties of elements are a periodic function of their atomic numbers
9.
The Modern Periodic Table has how many periods and groups?
A.
6 periods and 18 groups
B.
7 periods and 8 groups
C.
7 periods and 18 groups
D.
8 periods and 18 groups
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ANSWER :
C. 7 periods and 18 groups
10.
How many elements are present in the 1st, 2nd and 3rd periods of the Modern Periodic Table respectively?
A.
2, 10 and 18
B.
2, 8 and 8
C.
1, 8 and 18
D.
2, 8 and 18
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ANSWER :
B. 2, 8 and 8
11.
Elements in the same group of the periodic table have similar chemical properties because they have:
A.
The same atomic mass
B.
The same total number of electrons
C.
The same number of valence electrons (same outer electronic configuration)
D.
The same number of neutrons
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ANSWER :
C. The same number of valence electrons (same outer electronic configuration)
12.
The period number of an element corresponds to:
A.
The number of valence electrons
B.
The highest principal quantum number (n) of the outermost occupied shell
C.
The atomic number of the element
D.
The total number of electrons in the element
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ANSWER :
B. The highest principal quantum number (n) of the outermost occupied shell