Oxidation number is charge of element in compound. Can be neutral, positive or negative.
Oxygen in dichromate has oxidation number -2, becauce there are seven oxygens, net oxidation number of oxygen is -14.
2·x(oxidation number of Cr) + 7· (-2) = -2 2x= +12
x= +6, oxidation number of one chromium is +6.
When HCl is added to metal ions, metal chlorides are produced. In this problem, it is asked whether the given ions precipitate or not when added to HCl. According to the rule, all chlorides except Ag+, Pb 2+, Hg2 2+ are soluble. Hence the ion that would precipitate is only lead (II) ion.
Rr - Round eyes. the two alleles are R and r, and if R is dominant, the phenotype will be round
Increased upwelling in a coastal area results to more aquatic life. Upwelling is the process in which deep, cold water rises towards the surface. It is an oceanographic phenomenon that involves wind driven motion of the dense, cooler and usually nutrient-rich water towards the ocean surface replacing the warmer usually nutrient depleted surface water.
