Calculate the mass of NaOH required to make 300 CM3 of 0.2M solution

Which traits do human embryos have that link them to a common ancestor with fish and reptiles? a. scales and tail b. gill slits and scales c. tail and gill slits d. hair and tail

8.98 dm3 of hydrogen gas is collected at 38.8 °c. find the volume the gas will occupy at -39.9 °c if the pressure remains constant.

What does a numerical subscript following an element in a chemical formula mean?