If my problem statement is: Which mask filters air more effectively?

And my independent variable is: Type of mask

What's my dependent variable?

Which part of earth’s surface receives the most direct rays from the sun? a) equator b) ocean c) poles d) mountains

Answer explain why it is not possible to deduce a complete order of reactivity.

Observation and experimentation have led many scientists to accept a theory about the origin of the universe. this theory is called the big bang theory. scientific evidence collected and observed by scientists around the world suggests that the universe is ever expanding from a hot and dense initial state. what makes this a scientific theory? (2 points)