Select the correct mass for each of the samples described below. 3.01 × 1023 molecules H2O

8.32 × 1020 formula units CaBr2

1.93 × 1026 molecules XeF6

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

The bond energy for the van der waals bond between two helium atoms is 7.9×10−4ev. assuming that the average kinetic energy of a helium atom is (3/2)kbt, at what temperature is the average kinetic energy equal to the bond energy between two helium atoms

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.