In which order will free nucleotides add on to a single strand of dna with the sequence attgca during dna replication?

The answer is T A A C G T.

Replication is a process in which DNA molecule is copied, and thereby two identical DNA molecules are produced.  Complementarity is achieved through interactions between nucleobases. In the DNA, base complements are adenine - thymine (A-T) and guanine - cytosine (G-C). 

So, free nucleotides will add in the following order T A A C G T:
original strand                 new strand
     A                                       T
     T                                       A
     T                                       A
     G                                      C
     C                                      G
     A                                       T