Bài tập điện trở dòng điện nhánh

Explain the comparisons between nature and packingtown that appears on pages 81 and 82 answer

The star betelgeuse is about 600 light-years away. if it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space.b. we'll know it immediately because it will be brighter than the full moon in the sky.c. we won't know about it until 600 years from now.d. none of the above.

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?