Calculate the smallest increment of energy (a quantum) that can be emitted or absorbed at a wavelength of 812 nm.

How many ions that have a +1 charge will bond with an ion that has a -2 charge

Often on a topographic map, every fifth contour line is darkened. what is this line called? a. key b.slope c.benchmark d. index contour

Tin has ten stable isotopes. the heaviest, 124sn, makes up 5.80% of naturally occuring tin atoms. how many atoms of 124sn are present in 82.0 g of naturally occurring tin? what is the total mass of the 124sn atoms in this sample?