Please help asap! Find the percent composition of all the elements in the following compounds

K2Cr2O7: % K % Cr % O

Read these sentences from the text. near the equator, the tropics receive the most rain on a consistent basis. as a result, the fresh water falling into the ocean decrease the salinity of the surface water in that region. [. .] . . as the salt content of sea water increases, so does its density. what can you infer about how rain affects the density of surface water near the equator?

What is the subscript for oxygen in its molecular formula

What is the ph of a solution that has a hydrogen ion concentration of 1.0 * 10 -9 m?