The Hebrews were to get their own straw for making the mud-bricks yet still had to produce the same quantity as before. This straw was previously supplied them by the Egyptians so they could concentrate on making bricks only. They thus had to search out materials for themselves and were punished for not meeting their quota.
The Egyptian taskmasters oppressed the Israelites, per Pharaoh's initiative (Exodus ch.1).
There was only 1 Pharaoh that enslaved the Hebrews, but his name is not mentioned in the Torah.
He enslaved them.
They were slaves to Pharaoh.
Because the Hebrews were starting to outnumber the Egyptians in population.
After the Pharaoh died, and the new Pharaoh took over, they were enslaved.
Matzoh
The Torah doesn't mention the name of the Pharaoh who enslaved the Hebrews.
makot(plaques)
Pharaoh, the one who wouldn't let the Hebrews go.
Passover celebrates the time when the Hebrews fled from Egypt and Moses led them, chasing after them was Pharaoh's army. Moses then parted the sea to let the Hebrews cross and closed the sea on Pharaoh's army. I xxx
Hebrews were never slaves in Egypt. There is no record of such thing beyond a book of bias written by the Jews.