28. An element “X” has five major isotopes, which are listed below along with their abundances. What is the element?
Isotope
Percent Natural Abundance
Atomic Mass
46X
47x
48x
49X
50%
8.00%
7.30%
73.80%
5.50%
5.40%
45.95269
46.951764
47.947947
48.947841
49.944792

Why do scientists look for patterns in the world? a. patterns can explain observations. b. patterns never change, no matter what. c. patterns are easy for scientists to detect. d. patterns are all the same, through all time.

For a research project, a student decided to test the effect of the lead(ii) ion (pb2+) on the ability of salmon eggs to hatch. this ion was obtainable from the water‐soluble salt, lead(ii) nitrate, which the student decided to make by the following reaction. pbo(s) + 2 hno3(aq) → pb(no3)2(aq) + h2o losses of product for various reasons were expected, and a yield of 86.0% was expected. in order to have 5.00 g of product at this yield, how many grams of pbo should be reacted? (assume that sufficient nitric acid, hno3, would be used.)

Ineed pls urgent 1-20 in order and fully detail step my step.