The enthalpy of combustion of octane is -5470 kJ/mol. Octane (formulae C8H18) was used to heat some water in a copper can. The amount of octane used up was 0.1 g. The amount of water in the can was 100 cm3 . a) Find the moles of octane which was used up. (Show calculations)

Nebulae are enormous clouds in outer space. they are made mostly of hydrogen gas, helium gas, and dust. some nebulae glow brightly, while others do not. the stars that people see are huge, bright balls of glowing gas. they are made mostly of hydrogen and helium. which statement correctly describes other ways in which nebulae and stars are different? a. stars can form inside a nebula but a nebula can never be produced by any star. b. a star always has a higher density than a nebula. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star.