How many significant digits are in this number?
742800
1.6
2.5
3.4
4.3

3. There are 4 significant digits. The significant digits are 7428.

Ithink this is what you meant. the temperature at which a liquid begins to boil is called the boiling point. the boiling point of water is 212°f or 100°c.  and at that point will start to turn into steam (gas)