Oxidation number of strontium

Chlorophyll a had the molecular formula c55h72mgn4o5 how many atoms are in this molecule

Why is it possible for different microorganisms to extract energy not only from carbohydrates and other biological molecules but from a large variety of substances?

Calculate the molarity of each aqueous solution: a. 78.0 ml of 0.240 m naoh diluted to 0.250 l with water b. 38.5 ml of 1.2 m hno3 diluted to 0.130 l with water