Which element will have 6 occupied energy levels (rings) and 4 valence 1 electrons ?
A. Sn
B. Pb
C. Se
D. C

Initially, the balloon had 3.0 liters of gas at a pressure of 400 kpa and was at a temperature of 294 k. if the balloon is cooled to 277 k and its volume decreased to 1 l, what will the new pressure in the balloon be?

What is the density of the black hole

What are scientists who study fossils called? ( a ) astronomers. ( b ) biologists. ( c ) geologists. ( d ) paleontologists.