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प्रश्न
Write a scientific reason.
There was ambiguity about the correct position of hydrogen in Mendeleev’s periodic table.
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उत्तर
- Hydrogen resembles alkali metals. It has one electron in its outermost shell like alkali metals. Its valency is 1 like alkali metals. It forms oxides (H2O) similar to alkali metals (Na2O). However, hydrogen also resembles halogens. It is a diatomic molecule (H2) like halogens (F2, Cl2). It is one electron deficient to achieve stable electronic configuration similar to halogens.
- Due to this unique behaviour of hydrogen, it could not be decided whether the correct position of hydrogen is in the group of alkali metals or in the group of halogens.
Thus, there was ambiguity about the correct position of hydrogen in Mendeleev's periodic table.
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संबंधित प्रश्न
Fill in the blank:
The modern periodic table consists of ……………. periods.
Fill in the following blank with suitable word:
The basis for modern periodic table is ...............
What is meant by a period, in a periodic table?
Give two example of group 17 elements.
How were the positions of isotopes of an element decided in the modern periodic table?
On which side of the periodic table will you find metals?
On which side of the periodic table will you find non-metals?
The modern periodic table was prepared by ______.
The atomic particle whose number in the atoms of an element always remains the same and which forms the real basis for the modern classification of elements is:
(a) electron
(b) proton
(c) neutron
(d) meson
How does the chemical reactivity of the halogens vary on going in group 17 of the periodic table?
(b) What is the number of elements is 3rd period, the modern periodic table?
In what respects do the properties of group 1 elements differ from those of group 17 elements? Explain with examples by taking one element from each group.
What are the groups in a periodic table? Give two characteristics of each.
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Give reasons for your choice.
Name two elements in Inert gas.
Name two elements in each case:
Transition element
State its position in the periodic table?
State the main aim of classifying elements. Which is the more fundamental property of elements that is used in the development of Modern Periodic Table? Name and state the law based on this fundamental property. On which side of the periodic table one can find metals, non-metals and metalloids?
Give the symbol and valency of the following element and radical.
Nitrate
Give the symbol and valency of the following element and radical.
Bisulphite
Give the symbol and valency of the following element and radical.
Sulphate
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Give the chemical formula of sodium bicarbonate
Give the chemical formula of carbonic acid
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Name the following:
The group of the Modern Periodic Table to which calcium [Ca2+] belongs.
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Right or wrong sentence.
The modern periodic table has 1 to 7 periods.
______ is the longest period in the periodical table.
______ forms the basis of the modern periodic table.
An element which is an essential constituent of all organic compounds belongs to
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| Group No. → | 1 | 2 | 13 | 14 | 15 | 16 | 17 | 18 |
| Period ↓ | ||||||||
| 2 | A | B | ||||||
| 3 | E | D | F | C |
Write the molecular formula of the compound formed by the combination:
A and F
A part of modern periodic table is given below. On its basis, answer the following questions:
| Group No. → | 1 | 2 | 13 | 14 | 15 | 16 | 17 | 18 |
| Period ↓ | ||||||||
| 2 | A | B | ||||||
| 3 | E | D | F | C |
Which of the element is a Noble gas?
1H2 is an isotope of hydrogen. In the modern Periodic Table it will ______.
State the group and period, of the element having three shells with three electrons in valence shell.
Match the atomic number with the following:
An element of group 2.
