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प्रश्न
Why was this basis of classification discarded for future classification of elements?
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उत्तर
Basis of rejection:
- Some characteristics being considered, varied under different conditions.
- Certain elements resembled metallic as well as non-metallic both.
- It did not serve the purpose of classification.
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संबंधित प्रश्न
Rewrite the following statement after correction, if necessary:
Groups have elements with consecutive atomic numbers.
Find the neutral atom in the periodic table which has the same number of electrons as K+ and Cl−. What is this number?
Write the names and symbols of two very reactive metals belonging to group 1 of the periodic table. Explain by drawing electronic structure, how either one of the two metals reacts with a halogen. With which name is the bond formed between these elements known and what is the class of the compound so formed known? State any four physical properties of such compounds.
The non-metal A is an important constituent of our food and most of the fuels around us. A forms two oxides B and C. The oxide B is poisonous whereas oxide C causes global warming.
(a) Identify A, B and C.
(b) To which group of periodic table does A belong?
(c) Name another element which is placed in the same group as A.
What is the need for classification of elements?
Match the following
| 1. | Galvanisation | Noble gas elements |
| 2. | Calcination | Coating with Zn |
| 3. | Redox reaction | Silver-tin amalgam |
| 4. | Dental filling | Alumino thermic process |
| 5. | Group 18 elements | Heating in the absence of air |
Moseley’s periodic table is based on atomic mass.
The atom of an element has electronic configuration 2, 8, 7. To which of the following elements would it be chemically similar?
An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide.
- Identify the element
- Write the electronic configuration
- Write the balanced equation when it burns in the presence of air
- Write a balanced equation when this oxide is dissolved in water
- Draw the electron dot structure for the formation of this oxide
Relate the names of the following scientists with the statements given below.
Arranged elements in the increasing order of atomic mass.
