What are common compounds of selenium? What are they used for and where are they found? Please answer ASAP, please don’t send scam/spam.

Write a net ionic equation to show that hydrofluoric acid, behaves as an acid in water.

If a molecule with a molecular formula of c13h18 is treated with an excess of h2 in the presence of finally divided pt metal under conditions required for maximum hydrogenation of the molecule to give a molecule with a formula c13h24, how many rings are in the molecule?

Which is an example of the practical pursuit of alchemy? a. forming perfect substances. b. transforming base metals. c. developing metalworking techniques. d. linking spiritual characteristics with material substances.