De or het atoomexplosie?

The correct Dutch article is:

de atoomexplosie

Rule Words ending in -tie and -sie: almost always de. See the rule

How to use atoomexplosie

the atoomexplosiede atoomexplosie
this atoomexplosiedeze atoomexplosie
that atoomexplosiedie atoomexplosie
our atoomexplosieonze atoomexplosie
your atoomexplosiejouw atoomexplosie
every atoomexplosieelke atoomexplosie
which atoomexplosie?welke atoomexplosie?
a big atoomexplosie / the big atoomexplosieeen grote atoomexplosie, de grote atoomexplosie