12. Select two elements that can exhibit a negative oxidation state in compounds. 1) Kr 2) I 3) Cu 4) Ca 5) H

## Step 1<br />The oxidation state of an atom in a compound is the charge that it would have if all bonds to atoms of different elements were 100% ionic. <br /><br />## Step 2<br />Elements that can exhibit a negative oxidation state are those that are more electronegative than the hydrogen atom. This is because they have a greater tendency to attract electrons towards themselves.<br /><br />## Step 3<br />In the given options, Iodine (I) and Copper (Cu) are known to exhibit negative oxidation states. <br /><br />## Step 4<br />Iodine (I) can exhibit a negative oxidation state because it is more electronegative than hydrogen. <br /><br />## Step 5<br />Copper (Cu) can also exhibit a negative oxidation state because it can lose electrons to form a negative charge.