'A second is defined as the period of 9,192,631,770 oscillations of this element, symbl Cs'
cesium
GRAB BAG: A second is defined as the period of 9,192,631,770 oscillations of this element, symbl Cs
A second is defined as the period of 9,192,631,770 oscillations of this element, symbl Cs
A second is defined as the period of 9,192,631,770 oscillations of this element, symbl Cs
GRAB BAG
cesium
GRAB BAG