I NEED HELP!! PLEASE what is the predicted order of electronegativity values from least to greatest for elements in the second period?

A. li b>n>f
B. c b>n>f
D. there is no way to predict

Asolution has a ca2+ concentration of 0.049 m and an f- concentration is 0.147 m at equilibrium. the value of ksp for caf2 at 25°c is 4.0 x 10-11. will this solution form a precipitate? yes no

All of the following are part of the biosphere except

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.