Lead has an average atomic mass of 207.19 amu. The mass numbers of three isotopes of lead are 206, 207, 208 considering that Pb 207 and Pb 208 have equal abundance, calculate the percentage abundance of various isotopes of lead. (with explanation)​

The blackbody curve for a star name zeta is shown below. what is the peak wavelength for this star ?

15. which of the following is not human-caused groundwater pollution? a. water in an aquifer dissolves elements such as arsenic and mercury from surrounding rock. b. water in an aquifer is contaminated by leachate that seeps into the ground from a landfill. c. water in an aquifer becomes polluted with chemicals used in hydraulic fracturing, or fracking. d. water in an aquifer absorbs harmful bacteria from the drainage field of a septic tank.

An atomic nucleus is composed ofa)protons.b)protons and neutrons.c)protons and electrons.d)protons, neutrons, and electrons.