Classify as endothermic or exothermic (a) a combustion reaction for which DrH3 = −2020 kJ mol−1 , (b) a dissolution for which DH3 = +4.0 kJ mol−1 , (c) vaporization, (d) fusion, and (e) sublimation.

The answer for #3 is c but i don't know why

In an investigation that uses the scientific method, which step immediately follows making a hypothesis? o summarizing the results o asking a question o making observations designing an experiment mark this and retum save and exit next submit

After watching the video "zinc strip in copper nitrate solution", and reading the instructions, click on the link labeled "start" just below the drawing of the pencil tip. follow the direction to complete the 3x3 grid. answer the below questions for the portion of the activity in which sn(s) is placed in agno3(aq)