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CLASS - XI CHEMISTRY (Classification of Elements and Periodicity in Properties)

Topic: - Genesis of Periodic classification

 

1. How many elements are known at present? [1]
 

 

2. Who was the first scientist to classify elements according to their properties? [1]
 

 

3. What is the basis of triad formation of elements? [1]
 

 

4. Stale the modern ‘Periodic law’? [1]
 

 

5. Define and state Mendeleev’s periodic law. [1]
 

 

6. How did Mendeleev arrange the elements? [2]
 

 

7. Name the two elements whose existence and properties were predicted by
Mendeleev though they did not exist then.
[2]
 

 

8. Describe the main features of Mendeleev’s periodic table? [3]