Which of the following statements is true about scientific theories?
a. scientific theories are never proven.
b. scientific theories are proposed answers to questions.
c. scientific theories summarize patterns found in nature.
d. scientific theories become hypotheses.

Which of the following is not a major characteristic used to identify minerals? a. hardness c. density b. magnetism d. luster select the best answer from the choices provided a b c d i know it is not d

The greenhouse effect a. something that has occurred for millions of years b. an unnatural phenomenon caused by humans that maintains earths temperature range. c. the results of the differences in the angle of the suns rays d. an unnatural phenomenon that causes heat energy to be radiated back into the atmosphere

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?