Ionic Radii And Lattice Energy

To determine how many of the cations , , , and have ionic radii more than , we need to consider their ionic radii. The ionic radii (in pm) for these ions are approximately as follows:

Comparing each cation to (102 pm):

• (76 pm) <
• (138 pm) >
• (152 pm) >
• (167 pm) >

Thus, the number of cations with ionic radii more than is 3. This value fits within the expected range of 3,3, confirming its correctness.

Therefore, the answer is: 3