- F, T Cesium, being an alkali metal, will lose an electron much more
easily than a transition metal like nickel would and so would be
higher on the activity series. This also means that cesium is a stronger
reducing agent than nickel; therefore, nickel must be a stronger
oxidizing agent than cesium is.
- B Do some simple oxidation/reduction arithmetic. Sodium starts with
an oxidation state of 0 because it isn’t in a compound. When Cl is in a
compound, its oxidation state is usually −1. In NaCl, Cl has an oxidation
state of −1, and Na has an oxidation state of +1. The oxidation state of Na
was 0 and is now +1; Na has lost electrons—it has been oxidized. Choice
(B) is the correct answer.
- A Again, some simple oxidation/reduction arithmetic is necessary.
Oxygen’s oxidation state here is −2. Since there are 4 oxygen atoms in the
formula, oxygen contributes total oxidation of (−2)(4) = −8. Potassium’s
oxidation state is +1. The oxidation state of the overall compound is 0. So 1
- (−8) + x = 0. x = +7. That’s why (A) is correct.
- E Let’s begin by applying the rules for assigning oxidation states to the
given reaction.
2Al^0 + 6H+1 Cl−1 → 2 Al+3Cl−1 3 + 3H^02
Notice that each mole of Al that’s oxidized to Al+3
loses 3 moles of electrons, so 2 moles of Al lose 6
moles of electrons during oxidation. The 6 moles of
electrons that are given up by Al are acquired by H+
ions to form H 2 . Choice (E) is the correct answer.
