Which states of a hydrogen atom can be excited by a collision with an electron with kinetic energy K

An animal cell loses the ability to convert energy stored in food to energy that the cell can use. which of the cell's organelles has stopped working? a. the mitochondria b. the nucleus c. the vacuoles d. the endoplasmic reticulum

What is the empirical formula of a compound that is 50.7% antimony and 49.3% selenium ?

The most common form of matter in the universe