Mendeleev’s Periodic Table consists of ‘X’ horizontal rows called periods and ‘Y’ vertical columns called groups. ‘Y’ and ‘X’ respectively are7 and 68 and 77 and 86 and 7

The statement seems to be a bit confusing, but I'll try to clarify it.

Dmitri Mendeleev's Periodic Table is organized into horizontal rows and vertical columns. The horizontal rows are called 'periods' and the vertical columns are called 'groups'.

In the modern periodic table, there are 7 horizontal rows or periods (from period 1 to period 7).

The number of groups can be a bit tricky because it depends on how you count them. If you count the transition metals (the block in the middle of the table) as individual groups, then there are 18 groups in total. However, if you count the transition metals as a single group, then there are 8 groups (from group 1 to group 8).

So, 'X' which represents the number of periods is 7 and 'Y' which represents the number of groups can be either 18 or 8, depending on how you count them.

The numbers 68 and 77, and 86 and 7 don't seem to correspond to any specific feature of the periodic table.