2Na3PO4 + 3Ca(NO3)2 --> Ca3(PO4)2 + 6NaNO3 If 4.1 grams of sodium phosphate reacts, how many grams of calcium phosphate is produced

What is a metal replacement reaction

Stage in which a typical star has completely stopped fusion

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