It's a great idea for a quiz. I do think though that your choice of wars could be changed and/or expanded. "Deadliest battles throughout history" is a great title, but it's let down a bit by some battles that would hardly merit the term 'battle' when compared to some of the really huge battles from history... even going back as far as the Egyptians/Assyrians, Greeks etc these are comparitively tiny. To say nothing of some of these Chinese wars... the mongol invasions... some of the fighting in South America etc. I'd highly encourage you to do a sequel!
for once I agree with Ozchris. The title is deceptive, and though taking away the Battle of Bunker Hill would remove one of the few answers I got right, it certainly looks like a barely a scuffle when stood up next to the siege of Stalingrad. Even some famous WW2 battles that were not included make Bunker Hill or Yorktown look insignificant, like the Normandy invasion. Then if you look at older battles you see things like the Mongol conquest of Baghdad with over 2 million casualties, or the Battle of Kalinga with 1.5 to 2 million, and what about the siege of Leningrad and Operation Barbarossa? Those are from wars that you included in the quiz but resulted in more casualties than Stalingrad by most estimates. I know it's very hard to get consistent numbers... estimates vary wildly depending on which account you're going by and some include civilians and collateral deaths while others do not...
I thought Antietam would be on here but I guess that only has the record for most killed on a single day (in American history), and you already have two other battles from the Civil War.
The ranking for WW1 battles is wrong and throws the whole quiz into doubt. While the casualty figures for Somme and First Marne are correct, the Somme was only the 3rd deadliest battle and First Marne the 7th deadliest battle. The highest casualties were incurred in the 2 main battles of the last year of the war - the failed German Kaiserschlacht or Spring Offensive (1.5m) and the victorious Allied 100 days offensive from Amiens to the Armistice (1.8m). I suspect there are inaccuracies in the other wars I don't know as well...