The mass of a proton is ##1.67*10^(-27)## kg. What is the mass of a proton in picograms?

The mass of a proton in picograms is ##1.67 * 10^(-12)"pg"##.

This is a basic problem in which you must go from one order of magnitude, in your case kilograms, to another order of magnitude, picograms.

As you can see, 1 kg contains ##10^(3)"g"##, and 1 g contains ##10^(12)"pg"## . In other words, you get ##10^(3)"g"## for every 1 kg and ##10^(12)"pg"## for every 1 gram.

So, set up two conversion factors to take you from kg to grams, and then from grams to picograms

##1.67 * 10^(-27)cancel("kg") * (10^(3)cancel("g"))/(1cancel("kg")) * (10^(12)"pg")/(1cancel("g")) = color(green)(1.67 * 10^(-12)"pg")##