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प्रश्न
State the merits of Mendeleev's classification of elements.
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उत्तर
Merits of Mendeleev's classification of elements:
- Grouping of elements
- Gaps for undiscovered elements: Mendeleev left some gaps in his periodic table for subsequent inclusion of elements not known at that time.
- He predicted the properties of the then-unknown elements on the basis of properties of elements lying adjacent to the vacant slots (eka-aluminum and eka-silicon).
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संबंधित प्रश्न
In the classification of the them known elements, Mendeleev was guided by two factors. What are those two factors?
Which group of elements could be placed in Mendeleev's periodic table later on, without disturbing the order? Give reason.
State the merits of Mendeleev's 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?
Why could no fixed position be given to hydrogen in Mendeleev's periodic table?
Find the odd one out and give its explanation.
Write the name.
The family of elements having zero valency.
Write scientific reason.
In a group, the size of the atom increases as it goes down from the top.
Match the column:
| Column ‘A’ | Column ‘B’ |
| Alkali metals | (a) Group 18 |
| Halogens | (b) Group 1 |
| Noble gases | (c) Group 17 |
