Question: What is the Lap Length of the race with a Grand Prix FIA Category?
SQL: SELECT "Lap length" FROM "2-15179545-1" WHERE "Category" = 'Grand Prix FIA';

Question: What is the Race on July 30, 1950 with a Formula 2 FIA, non-championship?
SQL: SELECT "Race" FROM "2-15179545-1" WHERE "Category" = 'Formula 2 FIA, non-championship' AND "Date" = 'July 30, 1950';