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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
Why do you think the noble gases are placed in a separate group?
What property do all elements in the same column of the Periodic Table as fluorine have in common?
What was the Mendeleev's basis for the classification of elements?
Why did Mendeleev leave some gaps in his 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 _______.
Eka boron : Scandium : : Eka Aluminum : _______
Find the odd one out and give its explanation.
Write scientific reason.
In a group, the size of the atom increases as it goes down from the top.
Describe the merits of Mendeleev’s periodic table?
