Mine are 7 weeks. They have been in there coop 3 nights. I have been keeping it no colder than 53. However it is warmer under the light. I am just going off some advice given to me on this site. It seems 50 may be a little cool for that age, but Im not certian. I would try to warm it up a bit. We put a small space heater in our coop as it is still snowing here and getting down in the teens at night.
I have 3, 5 week old birds in my den because it is still getting down in the 40's at night and only the 50's during the day....
I would say no unless you have a heat lamp in your coop. They don't have all thier feathers yet.
Chicks are not feathered with mature feathers to retain heat and regulate body temps until 8 - 10 weeks. Some breeds need 12 weeks. Without a lamp those chicks will suffer from the cold. Remember when a chick gets chilled it has a hard time recovering and it can be fatal.