alpha carbon
source: Illustrated Glossary of Organic Chemistry The alpha-carbon is the first carbon next to a functional group which is not involved in that group. In this example (Picture) any C to the left or right to the C=O is in alpha-position relative t...
Alpha C is that Carbon to which the functional group is attached and BETA CARBON is the C attached to ALPHA CARBON. In ur question, ALPHA C is the C attached to CHO group and BETA C is the left most C. HOPE I HELPED YOU!