What element can you substitute to mercury in making battery

Which of the following ocean acidification? are the most likely side effects of a ph less than 7.0 in the ocean b. more metal salts altering the ocean chemistry c. dissolution of the shells of marine organisms d. both a & b e. all of the above.

When balancing a chemical equation:

Match the formula for the following compound:   magnesium sulfate heptahydratemgs·7h2omg2so4·7h2omg(so4)2·7h2omgso4·7h2o