All materials are made up of elements. Which of the following best describes elements?

A.
Mixtures combine in several different ways to make many kinds of elements.
B.
Compounds combine in several different ways to make a limited number of elements.
C.
Elements combine in several different ways to make many kinds of compounds.
D.
Elements are unable to combine in order to make different compounds.

STUDY ISLAND

What type of electromagnetic wave is used in security pens? a. x-rays c. microwaves b. visible light d. ultraviolet radiation select the best answer from the choices provided

This is important 1. what happens to the speed of molecules in water vapor when it condenses to form a liquid? (2 points) the molecules slow down. the molecules speed up. the molecules slow down and then speed up. the molecules speed up and then slow down. 2. how might human activities change to compensate for a decrease in water supplies? (2 points) humans might build a factory. humans might build drainage systems. humans might extract more water from the ground. human behavior does not change because of the water cycle. i'll be grateful if anyone can answer these 2 questions !

A0.750 kg aluminum pan is removed from the stove and plunged into a sink filled with 10.0 kg of water at 293 k. the water temperature quickly rises to 297 k. what was the initial temperature of the aluminum pan? the specific heat of aluminum is ca = 900 j/(kgk) and water is cw = 4190 j/(kgk)