Please answer correctly and no links

What were major causes of the dust bowl apex

1. why didnt the league of nations(lon) stop germany and italy from being aggressive towards other nations before the war? a. the lon supported german and italian aggression b. the lon was only concerned about japanese aggression c. the lon didnt have an army or real power to enforce what it wanted d. the lon was busy solving the spanish civil war2. why did allied powers try to appease nazi germany before ww11? a. all the following were reasons for appeasement b. world war 1 was so terrible that many leaders never wanted another war c. many people thought the newly-streangthened soviet union was a bigger threatd. many leaders wondered if they could win another war or if their old allies (like america) would even join their side this time 3. at the end of the war what 2 countrys emerged as global superpowers? (2) a. the united states b. great britain c. france d. the union of soviet socialist republics e. germany

Ascientist performs an experiment where she measures the mass of a piece of metal, pours acid onto the metal, washes the metal, and then re-measures the mass of the metal. the scientist repeats the experiment several times, each time increasing the amount of acid used. the dependent variable in the experiment is the: initial mass of the metal final mass of the metal amount of acid used washing the metal