Which statement about Delta. Hf is true?
It is zero for any compound in its standard state.
It is positive when the bonds of the product store more energy than those of the reactants.
It is negative when a compound forms from elements in their standard states.
It is zero for any element that is in the liquid state.

Explanation:

ΔHf is the change of enthalpy during the reaction, which is equal to the sum of enthaply  changes of the products less the sum of the enthalpy changes of the reactants.

Also, ΔHrxn, per definition, is the potential chemical energy stored in the bonds of the products less the chemical potential energy stored in the bonds of the reactants.

Then, when the potential chemical energy stored in the bonds of the products is greater than the chemical potential energy stored in the bonds of the reactants ΔHrxn is positive.

Hence, you conclude that ΔHf is positive when the bonds of the product store more energy than those of the reactants (second statement from the choices).

Some brief comments about the other statements:

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

sorry i was late, but i don't know what assignment your talking about, i'm in flvs as well, im in earth space science. but u are behind pace bc every class should be in the 3's or 4'