What must models and theories do in order to remain valid? Provide 2 facts.

A planet similar to Earth has four moons roughly the same distance away. The moon that will MOST affect tides on the planet is the one that has the greatest A) mass. B) volume. C) density. D) amount of water.

How could you determine if a car door is made of a material, such as plastic?

In the balanced redox reaction: 2 cu (s) + s (s) ? cu2s (s), how many electrons are gained or lost by each sulfur atom?

Rank from most to fewest valance electrons

The Minoan civilization existed on the island of Crete, and it was influential in the Mediterranean during the 2000s BCE. In which way can the Phoenicians be described as successors to the Minoans? A. Phoenicia had a powerful, well-trained army. B.

Which one of the following is a redox reaction?. 2 Na (g) + Cl2 (g) 2 NaCl (s) A. K2Cr2O7 (aq) + 2 KOH (aq) 2 K2CrO4 (aq) + H2O (l) B. H2O (l) H + (aq) + OH - (aq) C. Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (l) D.

Name 4 common chemical properties of matter

Why is photosynthesis so important to plants, and can't animals use it?

One way the government of Kim Jong-il controls the lives of the people who live in North Korea is by a. requiring every citizen to vote. b. controlling information its people receive from the outside world. c. enforcing free trade with other nations.

Give reasons 1) copper utensils and sheets become blackish after some days