Which of the following pairs of elements would form a covalent compound? calcium/phosphorous
copper/fluorine
sodium/ sulfur
nitrogen/ oxygen

For the following dehydrohalogenation (e2) reaction, draw the zaitsev product(s) resulting from elimination involving c3–c4 (i. e., the carbon atoms depicted with stereobonds). show the product stereochemistry clearly. if there is more than one organic product, both products may be drawn in the same box. ignore elimination involving c3 or c4 and any carbon atom other than c4 or c3.

Can someone me with questions 12 and 13 plz.

The excretory system, need answers for all: )