What is basic of matter that can’t be broken down

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

What is the subscript for oxygen in its molecular formula

When 13.3 g koh is dissolved in 102.7 g of water in a coffee-cup calorimeter, the temperature rises from 21.4 °c to 31.53 °c. what is the enthalpy change per gram of koh (j/g) dissolved in the water? * take the density of water as 1.00 g/ml. * assume that the solution has a specific heat capacity of 4.18 j/g*k. enter to 1 decimal place. do not forget the appropriate sign /(+). canvas may auto-delete the (+) sign