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प्रश्न
In the classification of the them known elements, Mendeleev was guided by two factors. What are those two factors?
उत्तर
In the classification of the then known elements, Mendeleev was guided by two factors, which are:
1. Increasing atomic masses
2.Grouping together of elements having the same properties
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संबंधित प्रश्न
State the periodic law on which Mendeleev's periodic table table was based. Why and how was this periodic law changed?
What name were given by Mendeleev to the then undiscovered element gallium?
Why did Mendeleev leave some gaps in his periodic table?
Which group of elements was missing from Mendeleev's original periodic table?
Mendeleev predicted the existence of certain elements not known at that time and named two of them as eka-aluminium, and eka-silicon.
(a) Name the element which has taken the place of (i) eka-aluminium, and (ii) eka-silicon
(b) Mention the period/periods of these elements in the modern periodic table.
(c) Write the group/ groups of these elements in the modern periodic table.
(d) Classify these elements as metals, non-metals or metalloids.
(e) How many valence electrons are present in the atoms of each of these elements?
The elements from the zero group are called _______.
Two elements in the same position : demerit of Newland's octaves : : place for Isotopes : _______
Match the columns.
| Column A | Column B |
| 1) Eka-aluminium | a) Scandium |
| 2) Eka-Silicon | b) Gallium |
| 3) Eka- boron | c) Germanium |
| d) Beryllium |
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 |
Write the name.
The family of elements having zero valency.
