What is A
and how does
B_on Earth affect a liquid boiling?

i think a, hope it .

explanation:

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.