What scenario is avoided because the constitution contains the supremacy clause

The supremacy clause avoids the scenario in which a law may be passed that contradicts or goes against the constitution. If something were to happen in the future, this would be called tyranny.

it further strained relations between the north and the south and convinced

it provided for selection of government employees through competitive examinations. it also made it unlawful to fire or demote covered employees for political reasons or to require them to give political service or payment, and it set up a civil service commission to enforce the law.

explanation: