The statement that is not correct for the periodic classification of element is
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Solution
The electrons are not filled in d-sub shell monotonically with increase in atomic number among transition elements.
The screening effect of ‘d’ electrons is
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Solution
The screening effect follows the order s > p > d > f.
Which one of the following is an amphoteric oxide ?
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Solution
Na2O (basic), SO2 and B2O3(acidic) and ZnO is amphoteric.
An atom has electronic configuration 1s22s22p63s23p63d34s2, you will place it in which group?
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Solution
The electronic configuration clearly suggest that it is a d-block element (having configuration(n– 1)d1 – 10 ns0 – 2) which starts from III B and goes till II B.
Hence with d3 configuration it would be classified in the fifth group.
The electronic configuration of an element is 1s22s22p63s23p3. What is the atomic number of the element, which is just below the above element in the periodic table?
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Solution
Atomic number of the given element is 15 and it belongs to 5th group.
Therefore atomic number of the element below the above element = 15 + 18 = 33.
Which of the following metals shows allotropy?
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Solution
Allotropy is characteristic property of group 14 elements.
All elements of group 14, except Pb, show allotropy.
Sn has three allotropic forms grey tin, white tin and rhombic.
Most acidic oxide is :
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Solution
Oxides of non metals are acidic in nature.
P is a non-metal and its oxides are acidic Rest of the oxides are basic because they are oxides of metals.
Which one of these is basic ?
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Solution
Basicity of oxides decreases in a period from left to right.
Na2O is basic oxide, CO2, SiO2 and SO2 are acidic oxides.
Alternatively, oxides of metals (e.g., Na2O) are basic, while oxides of non-metals (SO2, SiO2 and CO2) are acidic.
Which of the following is the atomic number of metal?
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Solution
Elements having 1, 2 or 3 electrons in its last shell act as metals.
32 = [Ar] 3d104s2p2
34 = [Ar] 3d104s2p4
36 = [Ar] 3d104s2p6
38 = [Ar] 3d10, 4s2p6, 5s2
Which group of periodic table contains no metal:
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Solution
Group IA and III A contain mostly metals.
Group VIII contains transition elements which are metals.
Group VII A contains mostly non-metals (F, Cl, Br).