Pls help ASAP PLEASEEE

The enthalpy of formation of water is -285.8 kj/mol. what can be inferred from this statement?

How to convert a density of 0.791g/cm3 to lb/ft3

Which set of characteristics best describes igneous rock? a) largest type of rock, made of organic matter, hardest type of rock b) least abundant type of rock, made of other rocks, made mostly of minerals c) found on all continents, contains wavy bands of stripes, contains fossils d) most abundant type in earth's crust, made of magma/lava, contains no fossils