What is period group and block of 3d??4s?

Dear student
Your question appears to be incomplete. 
Although assuming your question to be about 3d4s filling and their location, I am providing a solution below.
We know, the electrons in orbitals fill up according to increasing order of energy, since energy of 4s is less than that of 3d ; hence, 4s gets filled up before 3d.
So, in an element with 3d04s1 and 3d04s2 the element belongs to s- block and 4th period.
But the next electrons gets filled up in 3d so, next atomic number would correspond to 3d14s2, there are 10 electrons in 3d, hence 10 elements would be present in d-block, so the element with 3d14s2 corresponds to 4th period, 3rd group and d- block.

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