A 6.0 M solution using 126 grams of HNO3

Which statement describes the appearance of a temperature-vs.-time graph? a horizontal line shows that the temperature increases at a constant rate over time. a vertical line shows that the temperature decreases at a constant rate over time. horizontal lines where the temperature is constant during phase changes connect upward-sloping lines where the temperature increases. horizontal lines where the temperature increases are connected by upward-sloping lines where the temperature is constant for each phase.

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

What is the temperature of one mole of helium gas at stp?