[07.06] which of the following chemical reactions is an oxidation-reduction reaction? (2 points) wo3 + 3h2 yields w + 3h2o kno3 + licl yields lino3 + kcl caso4 + 2nacl yields na2so4 + cacl2 mg(no3)2 + 2hbr yields mgbr2 + 2hno3

Oxidation reduction reaction or redox reactions are those in which there is change in oxidation number of any element

In general oxidation is defined as gain of oxygen or loss of electron or hydrogen by an atom. Reduction is defined as gain of electron or hydrogen or loss of oxygen by an atom.

Let us consider each reaction one by one

1)

Here the oxidation number of W changes from +6 to 0 [reduction]

The oxidation number of H changes from 0 to +1 [oxidation]

Hence it is an oxidation reduction reaction

2)

Here there is no change in oxidation number of either element hence it is not oxidation reduction reaction

3)

Here there is no change in oxidation number of either element hence it is not oxidation reduction reaction

4)

Here there is no change in oxidation number of either element hence it is not oxidation reduction reaction

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.