Help plzz asap ignore the answers i put in their wrong

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.

Blank allows you to do calculations for situations in which only the amount of gas is constant a)boyle's law b)combined gas law c)ideal gas law d)dalton's law

What’s the scientific notation for the number 6,840,000,000