'This second-lightest metal, symbol K, is so soft it can be cut with a knife'
Potassium
SCIENCE: This second-lightest metal, symbol K, is so soft it can be cut with a knife
This second-lightest metal, symbol K, is so soft it can be cut with a knife
This second-lightest metal, symbol K, is so soft it can be cut with a knife
SCIENCE
Potassium
SCIENCE