<u>Answer:</u> The mass percent of lead in lead (IV) carbonate is 63.32 %
<u>Explanation:</u>
The given chemical formula of lead (IV) carbonate is 
To calculate the mass percentage of lead in lead (IV) carbonate, we use the equation:

Mass of lead = (1 × 207.2) = 207.2 g
Mass of lead (IV) carbonate = [(1 × 207.2) + (2 × 12) + (6 × 16)] = 327.2 g
Putting values in above equation, we get:

Hence, the mass percent of lead in lead (IV) carbonate is 63.32 %
Answer:
The coefficient before potassium (K) balances this chemical equation is 2.
Explanation:
_K +Cl₂ → 2KCl
K =1 ; Cl =2
K=1 × 2 = 2
Cl = 1 × 2 = 2
2 K +Cl₂ = 2 KCl
The element that has the fewest valence electrons available for bonding I believe is Hydrogen.