how many moles are in 9.8 grams of calcium?

A volume of 18.0 L contains a mixture of 0.250 mole N 2, 0.250 mole O 2, and an unknown quantity of He. The temperature of the mixture is 0 ∘ C, and the total pressure is 1.00 atm. How many grams of helium are present in the gas mixture?

Nonmetals rarely lose electrons in chemical reactions because?

Write a checklist with at least three entries for how you can evaluate whether scientific information is reliable.

List the stars below from coolest to hottest. Sirius Betelgeuse Rigel Sun Arcturus

What must be done to be certain that a chemical change has taken place? a. Check for the production of bubbles before and after the change. b. Demonstrate that a release of energy occurred after the change. c.

Which of the following units is best when measuring the mass of an object?

When balancing an equation, should you adjust the subscripts or the coefficients?

How does the sun warm the earth

What controls the amount of light that enters the eye?

The universe contains billions of galaxies, each containing billions of stars. True or false