A sample of Argon-39 had an initial mass of 1.00 kg. After 150 years, the same sample has a mass of 0.6795 kg. What is the half life or argon 39?

prndulum needs thread, weight clock to time swings

the best answer for these questions would be:

1.            c. is smaller

2.            d) concrete operational

3.            b) interaction with the environment – the children interact with their environment can them learn more.

4.            a) parents who reason openly with children can limit a child’s cognitive ability.