Which substances have Delta. Hf = 0 kJ/mol by definition? Select all that apply. O2(g) N(g) H2O(l) Br2(l) Fe(s) He(g) S6(s).

1) this is the structure in the cell nucleus that houses a cell's genetic information

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

Does the number of ions in solution increase, decrease, or remain constant? it continuously decreases. it continuously increases. it decreases at first, then increases. it increases at first, then decreases.