Natural gas and petroleum are mostly alkanes t/f

True

Explanation:

Petroleum and natural gas are both fossil fuels. They contain a mixture of hydrocarbons but they commonly have alkanes as their composition. The petroleum and natural gas produce after the degradation and decomposition of the organic matter generated after the dead and decaying plant and animal matter under the heap of sediments for long years. The natural gas specifically have methane, butane and propane. Therefore, on the basis of the above description, this can be said that natural gas and petroleum are mostly alkanes.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"