Why will the crucible and its contents gain mass when heated?

The crucible will gain mass upon heating due to the formation of new compounds like oxides

Explanation:

The increase in mass of the crucible and its contents upon heating can be attributed to the formation of new compounds specifically oxides.

For example when a piece of magnesium placed in a crucible is heated and then weighed, there would be an increase mass. This is due to the reaction of magnesium (Mg) with air (O2) resulting in the formation of magnesium oixide (MgO) as per the following equation:

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.

answer:

the reaction is type of combination reaction.

explanation:

on the product side, there are 2 molecules of bonded to fe   which means one atom of fe are combined two molecules of . so, balanced chemical equation becomes :

this reaction follows the reaction type of combination reaction. a combination reaction is defined as chemical reaction in which reactants combines together to form a single product.