How many moles of atoms are in 3.09•10^23 He

At room temperature, none of the metals are a. soft. b. liquids. c. malleable. d. gases.

If you compared 1 m solutions, was a 1 m nacl solution more or less hypertonic than a 1 m sucrose solution? what is your evidence? what about 1 m nacl and 1 m glucose and 1 m sucrose?

Carbon-14 has 6 protons and 8 neutrons; which element has 6 protons and 7 neutrons? c-13 si-14 c-6

What is the absolute magnitude of the rate of change for [NH3) if the rate of change for [H] is 2.00 M/s in the reaction 2 NH3 (g) - N2 (g) + 3 H2 (g) ?

Potassium-40 decays to argon-40 with a half-life of 1.27*109 yr. What is the age of a rock in which the mass ratio of 40Ar to 40K is 4.2?

What is an isotope? Give an example of an element with isotopes.

Consider the reaction between liquid water and aqueous magnesium nitride to form solid magnesium oxide and ammonia gas. If magnesium nitride is present in excess, how many moles of water are needed to form 9.17*1023 ammonia molecules?

The properties of elements are arranged by ... A. mass numbers B. atomic masses C. atomic radii D. atomic numbers

When a tire is inflated with air is it a chemical or physical change?

Which isotope is used to date ancient artifacts such as fossils? carbon-12 carbon-14 uranium-238 oxygen-16