31 which notations represent different isotopes of the element sodium? (1) 32s and 34s (3) na+ and nao
(2) s2- and s6+ (4) 22na and 23na

Iknow #2 is d. i just need to know why

Calculate the molar mass of aluminum oxide (al2o3). express your answer to four significant figures.

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