The melting and boiling points of a group of elements decrease as you go down the group, while their reactivity increases. a.. Are the elements from the first group or the second last group of the Periodic Table?
b ..Does this group consist of metals, metalloids, non-metals or a mix?
c.. Identify two elements in this group.

a) first group

b) metals

c) K - potassium, Li - lithium

Explanation:

a) they are the alkali metals

b) they're alkali metals lol

c) just look at a periodic table :P

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.