You are interested in how different air temperatures affect the speed at which gas molecules move. With a classmate, you have planned the following investigation: Choose a very hot day in the classroom.

The students close all of the windows and doors in the classroom and turn off any fans.
The students measure the temperature in the classroom with a thermometer.
One student stands in the corner of the classroom with a stopwatch.
Another student, 10 meters away in the opposite corner of the room, opens a container filled with a safe, but strong-smelling gas.
The student with the stopwatch measures the amount of time before they can smell the gas.
Repeat the steps above on a very cold day in the classroom.
Identify the independent variable in this investigation from the list below:

A. The temperature of the room
B. Amount of time before they smell the gas
C. The distance between the two students in the room
D. Not enough information is provided to identify the independent variable
E. The type of gas in the container

Solar energy is energy from the sun that is converted into thermal or energy. a. nuclear b. mechanical c. electrical d. chemical

Achemical reaction (also known as a chemical change) produces substances that are chemically different from the starting materials. an example of a chemical reaction is the formation of water from hydrogen and oxygen gas.in a physical change, a substance changes its physical appearance but not its chemical identity. an example of physical change is the formation of liquid water from solid water, a familiar process called melting. physically, liquid water looks very different from solid water (ice) but the chemical identity, water, is the same for both. which of following changes that affect the composition of our atmosphere involve physical changes and which involve chemical reactions? oxygen gas changes to ozone during thunderstorms carbon dioxide is produced by the combustion of gasoline in an automobile engine. when coal, oil, and natural gas are decomposed in landsills they produce methane gas. freezing rain develops when a warm air mass overrides a cold air mass. fog forms from water vapor when the temperature drops below the dew point

Write the empirical chemical formula of calcium with a mass percent of 38.8, phosphorus with a mass percent of 20.0, and oxygen with a mass percent of 41.3.