Question

The ratio of 2nd I.E. of He and 4th 1.E. of Be is
4.
2
2.​

Answer 1

Explanation:

Ionisation energy of H atom =13.6eV

Here, Be

3+

is H like atom.

∴ Ionisation energy of Be

3+

ion =13.6×Z

2

eV

=13.6×4

2

eV

=16×13.6eV

Now, ratio of their ionisation energy:

1E

Be

3+

1E

H

=

16×13.6eV

13.6eV

=

16

1

=1:16