A theory is an important part of science because it can be used to A. Create better questions B. Create better experiments C. Test a hypothesis D. Make predictions A student designed an experiment to test the affect of salt on the number of plants that live in water. What is the dependent variable in this experiment? A. The water B. Water temperature C. The number of plants living in the water D. The amount of salt in the water What is an appropriate way to analyze the results of an experiment A. Creating a graph B. Creating a data table C. Making observations D. Asking questions What is a control group used for? A. Making an observation B. Making a comparison C. Designing an experiment D. Making a hypothesis

Comedians like to joke that the reason we haven’t been visited by intelligent life from elsewhere in the universe is that aliens have been monitoring earth’s broadcasts of intellectually embarrassing tv programs, like gilligan’s island, fear factor, the jersey shore, and the jerry springer showand so consider us far too primitive to merit a visit. let’s check the assertion that aliens could have been receiving them. tv programs are broadcast at a frequency of about 100mhz with about 100kw of total power in 30frames per second, which emanatesroughly uniformly in all directions. assume that interstellar space transmits these broadcasts without attenuation. no matter how smart they are, aliens would require at least one photon per frame to interpret our signals. findthe number of photons per unit time per unit area reaching a receiver on a possible planet in the nearest star system, which is about 4 light-years away (a light-year is the distance light travels in a year). if aliens aimed a receiver or detector directly at earth, how big (in diameter) would it have to be to receive a photon per frame

How many hydrogen (h) atoms are in one molecule of sulfuric acid, h2so4? (1 points) 1 2 4 7

A100-watt light bulb illuminates a solar cell. the electricity from the solar cell operates a water pump that delivers 1 watt of power. what is the efficiency of the system?