Am i right in thinking that Cascade 220 is a DK weight yarn?
it’s recomendded for use on size 4.5 or 5 needles.
It’s either a sport or a DK weight, at that gauge.
It’s actually worsted weight – recommended for 4.5mm (US7) or 5mm (US8) needles. 
Oh, I just saw #5 needles, and that sounded like a sport or DK weight.
thanks - either way should do nicely for a pair of socks- MY FIRST EVER PAIR wish me luck
The 220 is a definite worsted weight.
Did you get the superwash version of Cascade 220? I wouldn’t use regular Cascade 220 for socks because you will have to handwash and if they ever wind up in the washing machine by mistake you’ll have a pair of baby felted socks. Also, for socks you should probably use a smaller needle than what is recommended on the label.