Should the federal legislature be able to repeal state laws in order to impose federal laws for the purpose of promoting the general welfare or common defense of the nation? if so, why? if not, why?

The federal legislature or congress can repeal the state laws under the necessary and proper clause in order to impose federal laws necessary to provide general welfare and common defense of the nation because they have the authority to do so. This authority was given to them because the people believed that the congress would decide for the common good.

Moreover, only the federal legislature has the right to contract debts, lay taxes and if they believed that a state law may prevent the collection of a federal tax, then they can repeal state laws making sure that it is for the benefit of the United States.