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प्रश्न
What name were given by Mendeleev to the then undiscovered element gallium?
उत्तर
Gallium(Ga) as eka-aluminium.
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संबंधित प्रश्न
What property do all elements in the same column of the Periodic Table as fluorine have in common?
Name two elements whose properties were predicted on the basis fo their positions in Mendeleev's periodic table.
The three elements predicted by Mendeleev from the gaps in his periodic table were known as eka-boron, eka-aluminimum and eka-silicon. What names were given to these elements when they were discovered later on?
State the merits of Mendeleev's classification of elements.
In Mendeleev's periodic table, why was there no mention of noble gases like helium, neon and argon?
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?
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 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 |
