Question

1. the main gas in earths atmosphere is
2. the second most common gas in earths atmosphere is
3. the ______ protects earth from the suns harmful uv rays.
4. when warm air rises and cool air sinks, it forms a ______, which helps move heat around the atmosphere.
5. in an experiment, the variable that is changed on purpose is called the
6. the variable that is measured or observed is the
7. a ______ is a visual way to show the relationship between variables or how data changes over time.
8. scientists ____ and ____ experiments to make sure results are correct.
9. only ______ variable can be changed in an experiment in order to know what caused the results.
10. the lowest layer of earths atmosphere, where all weather occurs, is the ______
11. the layer that contains the ozone layer, which protects us from harmful uv rays, is the ______
12. meteors burn up in the ______, creating \shooting stars.\
13. the northern lights happen in the ______
14. the outermost layer that blends into space is the ______

Explanation:

• Question 9: Nitrogen makes up about 78% of Earth's atmosphere, so it is the main gas.
• Question 10: Oxygen is about 21% of the atmosphere, making it the second - most common.
• Question 11: The ozone layer absorbs most of the Sun's harmful UV rays.
• Question 12: Convection currents are formed by the movement of warm (rising) and cool (sinking) air and help distribute heat.
• Question 13: The independent variable is the one deliberately changed in an experiment.
• Question 14: The dependent variable is what is measured or observed as a result of changes in the independent variable.
• Question 15: A graph is a visual representation of data relationships or changes over time.
• Question 16: Scientists repeat (do the same experiment multiple times) and replicate (have other scientists do the same experiment) to ensure accuracy.
• Question 17: To determine cause - effect, only one variable should be changed at a time.
• Question 18: The troposphere is the lowest layer where weather occurs.
• Question 19: The stratosphere contains the ozone layer.
• Question 20: Meteors burn up in the mesosphere.
• Question 21: The Northern Lights (auroras) occur in the thermosphere.
• Question 22: The exosphere is the outermost layer that blends into space.

Answer:

1. Nitrogen
2. Oxygen
3. Ozone layer
4. Convection current
5. Independent variable
6. Dependent variable
7. Graph
8. Repeat; Replicate
9. One
10. Troposphere
11. Stratosphere
12. Mesosphere
13. Thermosphere
14. Exosphere