Answer:
(c) Polyatomic
Explanation:
For a mono atomic gas, the specific heat at constant pressure is 5R/2. For a diatomic gas, the specific heat at constant pressure is 7R/2.
Since 11R/2 is larger than both 5R/2 and 7R/2 it cannot be mono atomic or diatomic hence the gas is polyatomic.
R is the gas constant.