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प्रश्न
In Mendeleev's periodic table, why was there no mention of noble gases like helium, neon and argon?
उत्तर
There was no mention of noble gases like helium, neon and argon in Mendeleev's periodic table as those gases were not known at that time.
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संबंधित प्रश्न
What were the criteria used by Mendeleev in creating his Periodic Table?
What property do all elements in the same column of the Periodic Table as fluorine have in common?
An atom has electronic configurations 2, 8, 7.
What is the atomic number of this element?
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 scandium.
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) 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.
