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प्रश्न
The basis of the classifications proposed by Dobereiner, Newlands and Mendeleev was ______.
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उत्तर
The basis of the classifications proposed by Dobereiner, Newlands and Mendeleev was atomic masses
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संबंधित प्रश्न
Rewrite the following statement after correction, if necessary:
Groups have elements with consecutive atomic numbers.
Why do we classify elements?
As element X has mass number 40 and contains 21 neutrons in its atom. To which group of the periodic table does it belong?
The following diagram shows a part of the periodic table containing first three periods in which five elements have been represented by the letters a, b, c, d and e (which are not their chemical symbols):
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1 18 a 2 13 14 15 16 17 b c d e
(i) Select the letter which represents an alkali metal.
(ii) Select the letter which represents a nobles gas.
(iii) Select the letter which represents a halogen.
(iv) What type of bond is formed between a and e?
(v) What type of bond is formed between d and e?
Alkaline earth metals have valency 2. This means that their position in the modern periodic table is in ______.
How did the early chemists classify elements?
What property forms the basis of identification?
What is the atomic number of elements of period 3 and group 17 of the Periodic Table?
An element with the atomic number 40 is placed in the period.
Complete the following cross word puzzle
Across:
(1) An element with atomic number 12.
(3) Metal used in making cans and member of Group 14.
(4) A lustrous non-metal which has 7 electrons in its outermost shell.
Down:
(2) Highly reactive and soft metal which imparts yellow colour when subjected to flame and is kept in kerosene.
(5) The first element of second Period
(6) An element which is used in making fluorescent bulbs and is second member of Group 18 in the Modern Periodic Table
(7) A radioactive element which is the last member of halogen family.
(8) Metal which is an important constituent of steel and forms rust when exposed to moist air.
(9) The first metalloid in Modern Periodic Table whose fibres are used in making bullet-proof vests
