1. Elements A, B and C constitute a Dobereiner’s triad. What is the relationship in their atomic masses?

2. How many elements were included in the arrangement given by Newland?

3. Which property of atoms was used by Mendeleev to classify the elements?

4. How many groups were originally proposed by Mendeleev in his periodic table?

5. Where in the periodic table are chemically similar elements placed, in a group or in a period?

6. Mendeleev’s periodic table had some blank spaces in it. What do they signify?

7. What name was given to the element whose properties were similar to the element eka-aluminium predicted by Mendeleev?

8. According to the modern periodic law the properties of elements are periodic function of which property of theirs?

9. List any two defects of Mendeleev’s periodic table which have been corrected in the modern periodic table?

10. How many group and periods are present in the long form of periodic table?