How can you tell if a chemical reaction has occurred?

As scientists search the universe for signs of life on other planets they are likely to focus on the presence of molecules containing which of the following elements? A. carbon B. calcium C. iron D. magnesium

Is Ba3N2 acidic basic or neutral

If you move an object from the base of a mountain to the top of the mountain what happens to its mass and weight

The quantum theory of energy levels within atoms was aided by: study of the sun's light spectrum emission line spectra of various elements alpha particles gamma rays

What pressure (in atm) will a sample of o2 gas occupy at 100.0 ml, if o2 has a volume of 25.00 ml at 2.0 atm?

If the specific heat of copper is 0.711 J/g•°C, how much copper would it take if the heat given off is 54.85 calories and the temperature change is 205°C.

Why is it is difficult to compress a liquid? a. liquid takes the shape of its container. b. the liquid particles flow away when compressed. c. liquid becomes solid when compressed. d. the liquid particles are very close together.

A mixture of two compounds, a and b, was separated by extraction. after the compounds were dried, their masses were found to be: 105 mg of compound a and 91 mg of compound b. both compounds were recrystallized and weighed again.

What are the five types of chemical reactions?

Which chemical reaction do plants use to take carbon dioxide out of the air