For the first question regarding the impact of the Intolerable Acts on the American colonies, the best response is:
The acts caused the colonies to unify against the British government.
The Intolerable Acts, which were punitive measures imposed by the British government in response to the Boston Tea Party, fostered a sense of solidarity among the colonies, leading to greater unity in opposition to British rule.
For the second question about British General Charles Cornwallis, the mistake that ultimately caused his defeat is:
He retreated to Yorktown where he was trapped.
Cornwallis's decision to concentrate his forces in Yorktown, combined with the arrival of French forces and the Continental Army, led to his encirclement and eventual surrender in 1781.