28. The specific heat of hydrogen gas at constant pressure

is C_p=3.4 x 10³ cal/kg  ⁰c and at constant volume is C_v= 2.4 x10³ cal/kg  ⁰c. _If one kilogram hydrogen gas is heated from 10 ⁰c  to 20⁰c  at constant pressure, the external work done on the gas to maintain it at constant pressure is

(a) 10⁵  cal                              (b)  10⁴ cal

(c) 10³   cal                              (d) 5 x 10³ cal

Ans. b