During a lab activity, students calculate the density of an element to be 7.78 g/cm3. The density listed on the periodic table is 7.13 g/cm3. Calculate the percent error and identify the element.

During a flame test, ions of a specific metal are heated in the flame of agas burner. A characteristic color of light is emitted by these ions inthe flame when the electrons (1) gain energy as they return to lower energy levels (2) gain energy as

Radium-221 has a half-life of 30 s. how long will it take for 95% of a sample to decay

A cube of aluminum is 20 cm on edge. aluminum has a density of 2.7 g/cm3 and a specific heat of 0.217 cal/g0c. what is the heat in calories needed to raise the temperature of the cube from 200 to 3000c?

Which best describes what happens when a person sees an orange T-shirt? A. The T-shirt radiates all colors of light except orange to human eyes. B. The T-shirt absorbs orange light from human eyes. C.

Compare the magnitude and rate of pH change of 1 M HCl added to DI water versus that of 1 M HCl added to your buffer solution. What changes and similarities did youobserve

What kind of group 1 atoms are the most reactive? a. Small atoms c. Atoms with the most electrons in the valence level b. Large atoms d. Atoms at the top of the periodic table

What does it mean when there are 2.3 x 10-4 moles?

Electric force is an A. attraction and repulsion between protons and electrons . B. attraction and repulsion between protons and neutrons. C. attraction and repulsion between neutrons and electrons.

A salt crystal has a mass of 0.18 mg. how many nacl formula units does it contain?

Which of the following is easist to accelerate? A. bowling ball B. tennis ball C. golf ball D. ping pong ball