Can someone plz explain ionic and covalent bonding !

State the formula for density in words and mathematical symbols

What amount of heat is exchanged when 106.2 grams of substance y goes from a liquid at 35 degrees celsius to a solid at the same temperature? melting point of substance y = 35 degrees c; δhvaporization = 3.67 j/mol; δhfusion = 3.30 j/mol. mwsubstance y = 28.22 g/mol. −12.4 j −3.51 x 102 j 1.24 x 101 j 351 j

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?