if an amendment violates the constitution,why should the Supreme court block its ratification?

How can an amendment violate the constitution? THe amendment once adopted is a PART of the consititution.
Now proposed amendments are all unconstitutional things, if they had been (and usually were) laws. Why else would they be proposed changes to the Constitution?
There is one exception to the SC getting into the fray and delaring the passed amendment unconstitutional: that is when the amendment was passed in an unconstutional manner.

The Supreme Court's role is to interpret the Constitution and ensure that the laws and actions of the government are in line with its principles. While it is true that once an amendment is adopted, it becomes part of the Constitution, there are instances where amendments may be considered unconstitutional.

An amendment can violate the Constitution if it contradicts or undermines the fundamental principles or rights protected by the Constitution. For example, if an amendment were to infringe upon the rights guaranteed by the Bill of Rights, such as freedom of speech, religion, or due process, it could be deemed unconstitutional.

Additionally, if the process for ratifying the amendment is itself unconstitutional, it could also be blocked by the Supreme Court. The Constitution provides specific procedures and requirements for the amendment process, and any deviation from these procedures could render the amendment invalid.

It is important for the Supreme Court to block the ratification of an unconstitutional amendment to ensure that the Constitution remains consistent and safeguards the rights and principles it was designed to protect. By fulfilling its role as the final arbiter of constitutional interpretation, the Court acts as a check on potential abuses of power and protects the integrity of the Constitution.