Use the solubility rules to determine if:
a. nacl will react with mgbr
b. koh will react with naci
c. mgs will react with naoh.

A reaction is said to occur if there is a formation of an insoluble solid or a precipitate(s) or a liquid (l) or a gas(g).

If both the reactants and products are in aqueous state, No reaction takes place.

All chlorides and Bromides are soluble except that of Ag, Hg and Pb.

Hence, No reaction takes place since all the reactants and products are in aqueous states.

Salts  of Group IA are soluble. Hence No reaction takes place

(REACTION TAKES PLACE)

All hydroxides are insoluble except that of Group IA, ammonium ion and  Group IIA down from Calcium.

Hence Reaction takes place with the formation of precipitate

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 answer for sodium is 0.186

the answer for rubidium is 0.251