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Question
In Mendeleev's periodic table, gap was not left for one of the following elements. This element is:
(a) gallium
(b) beryllium
(c) germanium
(d) scandium
Solution
(b) Beryllium.
In Mendeleev's periodic table, a gap was left for gallium, scandium and germanium.
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RELATED QUESTIONS
Besides gallium, which other elements have since been discovered that were left by Mendeleev in his Periodic Table? (any two)
Why do you think the noble gases are placed in a separate group?
State the merits of Mendeleev's classification of elements.
How do the properties of eka-aluminium element predicted by Mendeleev compare with the actual properties of gallium element?
State any three limitations of Mnedeleev's classification of elements.
Why could no fixed position be given to hydrogen in Mendeleev's periodic table?
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(a) EaO3
(b) Ea3O2
(c) Ea2O3
(d) EaO
Two elements in the same position : demerit of Newland's octaves : : place for Isotopes : _______
Match the columns.
| Column A | Column B |
| 1) Triads | a) Mendeleev |
| 2) Octave | b) Dobereiner |
| 3) Atomic number | c) Thomson |
| 4) Atomic mass number | d) Moseley |
| e) Newland |
Match the column:
| Column ‘A’ | Column ‘B’ |
| Alkali metals | (a) Group 18 |
| Halogens | (b) Group 1 |
| Noble gases | (c) Group 17 |
