For which of the following reactions is ΔH∘rxn equal to ΔH∘f of the product(s)?2Na(s)+Cl2(g)→2NaCl(s)H2 (g)+12O2(g)→H2O(g)Na(s)+12Cl2(g)→Na Cl(s)H2O2(g)→12O2(g)+H2O(g)2H2(g)+O 2(g)→2H2O(g)Na(s)+12Cl2(l)→NaCl(s)

1.solid

2.carbon dioxide

3.helium

qualitative observation deals with data that can be observed with our senses: sight, smell, touch, taste, and hearing. they do not involve measurements or numbers. for instance, colors, shapes, and textures of objects are all qualitative observations.