Easy for people from uk/!
t/f based on a very short text : )

False.

Clouds are gray because they collect water vapor. The more water vapor the clouds collect the thicker they become. The thicker the cloud, the grayer the cloud.  

False.

White clouds are thinner than gray clouds. White clouds allow more light to go through them so they look white. Grey clouds are denser and don't let as much light through.

True.

The relatively flat bottoms of clouds are always a little grayer than the sides. This is because they transmit less light.

i have heard the mermaids singing, each to each.

i do not think they will sing to me