| A very heavy, stable metal used to shield radiation is ____. |
carbon (C) |
| Lighter-than-air party balloons are filled with ____. |
copper (Cu) |
| About 21% of the Earth's atmosphere is ____. |
gold (Au) |
| All ____ atoms have six protons. |
helium (He) |
| A yellow, solid, nonmetal element is ____ (brimstone). |
lead (Pb) |
| A dense, radioactive, noble gas is ____. |
oxygen (O) |
| Bronze is an alloy of mostly ____ mixed with tin (Sn). |
radon (Rn) |
| The most malleable and ductile metal element is ____. |
sulfur (S) |
