Answer:
Reserves fall by $2 million, and the monetary base falls by $2 million.
Explanation:
In the books of First National Bank, the purchase of $2 million of bonds by First National Bank, from the Federal Reserve means there is a reserve with the Federal Reserve represented by security which stands as asset.
In the books of the Federal Reserve, The sales of bonds to First National Bank will create a liability from the reserve assets.
See attached for the T-accounts explain the answer