Briefly explain the powers of the national government

What will be an ideal response?

An ideal response would be:
The Constitution explicitly gives legislative, executive, and judicial powers to the national government. In addition to these delegated or express powers, such as the power to regulate interstate commerce and to appropriate funds, the national government has assumed constitutionally implied powers, such as the power to create banks, which are inferred from delegated powers. The constitutional basis for the implied powers of Congress is the necessary and proper clause. This clause gives Congress the right "to make all Laws which shall be necessary and proper for carrying into Execution the foregoing Powers, and all other Powers vested … in the Government of the United States."
In foreign affairs, the national government has inherent powers. The national government has the same authority to deal with other nations as if it were the central government in a unitary system. Such inherent powers do not depend on specific constitutional provisions but exist because of the creation of the national government itself. For example, the government of the United States may acquire territory by purchase or by discovery and occupation, even though no specific clause in the Constitution allows such acquisition.
The national and state governments may have their own lists of powers, but the national government relies on four constitutional pillars for its ultimate authority over the states: (1) the supremacy clause, (2) the war power, (3) the commerce clause, and especially (4) the power to tax and spend for the general welfare.