When the electron in hydrogen makes the the 2p to 1s transit

When the electron in hydrogen makes the the 2p to 1s transition, emitting a photon in the process, the angular momentum of the electron changes. Since angular momentum must be conserved even in quantum mechanics, where did the angular momentum go? Please be detailed and if possible provide a defense or reasoning!

Solution

Here, the angular momentum is conserved. The decreased angular momentum of the electron balances with the angular momentum along with linear momentum. of the generated photon.