3 At room temperature and pressure (rtp), which of the substances listed below is:
a a solid element?
b a liquid element?
ca gaseous mixture!
d a solid mixture?
e a liquid compound?
f a solid compound?
Bromine, carbon dioxide, helium, steel, air, oil,
marble, copper, water, sand, tin, bronze, mercury,
salt.

C

Explanation:

african americans demonstrated their newly found freedom by relocating often in search of relatives whom they had been separated from during slavery. others established schools to educate freed people and they built institutions such as churches and political organizations to advocate for their rights.