What is the meaning of "Hen Goyim k'Mar mi'Deli"?
Rashi: Nochrim who refuse to recognize their Creator, and He does not deem them worthy to establish Nevi'im from them to reveal to them His secrets, they are like a bitter drop filthy from the bottom of the bucket, sediment of the filth of the water and corrosion of the wood (slime).
Radak: Since Hashem did all this, how can the Goyim say that Hashem cannot take Yisrael from amidst them?! All of them are to Him like a drop in the bucket. It mentions a bucket, for drops spill from it when drawing water.
Malbim: The drop that drips from the bucket, it is nothing compared to the water in the bucket, but it is a part. So one nation is with respect to all the nations.
What is "Sachak Moznayim"?
Rashi: The copper corrodes, and it is Nischak (minced). Radak - this is a miniscule amount; it comes off when one blows.
Malbim: The dust on the scale is not even part of the scale. So everything found on the earth is nothing compared to the earth.
What is the meaning of "[Hen Iyim] ka'Dak Yitol"?
Rashi: [The islands will be] like fine powder; like dust that the wind raises, so the powder will be taken. Radak - so explain the Targum and the grammarian R. Yehudah Chiyug. Yitol is Nifal (will be taken).
Radak: When He will want, all the islands will carry them and convert them to something fine.
Malbim: The islands are totally insignificant compared to the earth.