Question

indicate the number of groups and periods in mendeleev's and modern periodic table.

Answer 1

8 groups and 7 periods are present in mandeleecs periodic table
hope it helps

Answer 2

Heya,

In Mendeleev periodic table there were seven horizontal rows called period but the periodic table that we have now only have six period this is bcz this period table was modified from time to time.
And in Mendeleev periodic table have eight vertical columns called group.


In the modern periodic table there are 7 horizontal rows called period and there are 18 vertical columns which is known as group.

Hope this helps...:)