A large rock falls freely from rest for 2 seconds. Approximately, how fast is it going?

It would be true sodium reacts with water in a violent way 

It must be measured in k.hope my answer is to you : )

The answer would be 25.3

Firstly, the planetary model of the atom  failed  to explain why individual atoms produce discrete  line spectra. in fact, according to rutherford's model, each individual atom should produce a  continuous  line spectrum. the second flaw to his model was the fact that electrons orbit the nucleus in a circular fashion.