The energies of the bonds broken in a certain reaction are greater than the energies of the bonds formed. Which one of the following statements about this reaction must be true? a. The reaction is endothermic.
b. The reaction is exothermic.
c. The reaction is spontaneous.
d. The reaction is non-spontaneous.

a. The reaction is endothermic.

Explanation:

The heat involved in a chemical reaction is given by the enthalpy change (ΔH), which is equal to the balance between the chemical bonds that are broken (release energy) and the chemical bonds that are formed (need energy):

ΔH ≅ bonds broken - bonds formed

If broken bonds > bonds formed ⇒ ΔH > 0 ⇒ endothermic reaction

Therefore, the reaction is endothermic (it requires energy).

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.

the product of the pressure and volume is also constant