Does a reptile play the same role as a bird in the plz hurry plz

Asingle atom of an element has 21 neutrons, 20 electrons, and 20 protons. which element is it? ok o z

This is a characteristic of the elements in the periodic table that shows a pattern. it may increase or decrease across or down the table.

If 34.2 grams of lithium react with excess water, how many liters of hydrogen gas can be produced at 299 kelvin and 1.21 atmospheres? 2 li (s) + 2 h2o (l) yields 2 lioh (aq) + h2 (g)