An atom contains 15 neutrons and has a mass number of 30. what is its atomic number? how did you determine the atomic number?

What happens to light waves from a star as the star moves away from earth?

The us government wants to allocate billions of dollars in the next 10 years to assure our future energy security. the funds will be spread among a variety of possible energy resources. where do you think the government should put the greatest support: solar energy, wind energy, clean coal, oil exploration, gas exploration, or a combination of sources? are there other efforts that should be explored? support your position with cited information for both questions.

An object moves from the position +34m to the position -15m in 15 seconds. what is it's total displacement? what is it's average velocity?