does any one know how to write it??

**Answer 1**

The electron configuration for Sr in its ground state is:

[Kr] 5s2

Sr2+ means that you are taking two electrons away from its valence shell. In this case, you take two electrons away from the 5s orbital. The electron configuration of Sr2+ is therefore, [Kr].

**Answer 2**

Sr 2 Electron Configuration

**Answer 3**

The answer is correct.

Don’t know why someone down voted

This is the answer mastering chemistry wants:

1s2s2p3s3p4s3d4p

That is the long hand

and the short hand should be [Kr]

Source(s): Mastering Chemistry

**Answer 4**

1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6.

the ground state is [Ar] 3d^10 4s^2 4p^6