Hydrogen mass is 1, the atom with mass number 7 is Lithium
They are called precipitates.
They both have two electron shells. Period indicates number of shells.
Answer:
It’s A
Explanation:
The nights are shorter. I just took the unit test review
Answer:
By contracting, muscles pull on bones and allow the body to move. ... For example, the biceps and triceps muscles work together to allow you to bend and straighten your elbow. When you want to bend your elbow, your biceps muscle contracts (Figure below), and, at the same time, the triceps muscle relaxes.
Explanation: