Please help

The rock in a lead ore deposit contains 89 % pbs by mass. how many kilograms of the rock must be processed to obtain 1.5 kg of pb?

What is the overall order of reaction for rate = k[no]2[o2]

The two naturally occurring isotopes of chlorine are 35cl (34.969 amu, 75.77%) and 37cl (36.966 amu, 24.23%). the two naturally occurring isotopes of bromine are 79br (78.918 rm amu, 50.69%) and 81br (80.916 amu, 49.31%). chlorine and bromine combine to form bromine monochloride, brcl. 1. how many peaks will be present in a mass spectrum for brcl? the four combinations of molecule possible given these four isotopes are: 81br37cl, 81br35cl, 79br37cl, and 79br35cl. 2. what are the masses of the four different brcl molecules? express the masses using six significant figures, in decreasing numeric order (highest to lowest), separated by commas.