Radioisotopes tell scientists that earth is how old?
a. 65 million years
b. 500 million years
c. 4.5 billion years
d. 13.4 billion years

Which element forms an ionic bond with flourine? 1) fluorine 2) carbon 3) potassium 4) oxygen

Agas diffuses 1/7 times faster than hydrogen gas (h2). what is the molar mass of the gas? 100.10 g/mol 98.78 g/mol 86.68 g/mol 79.98 g/mol

Which of the following units is not an official si unit