23. When an ideal gas in a cylinder was compressed isothermally by a piston, the work done on the gas was found to be

1.5×10⁴ J . During this process about

(a) 3.6×10³  cal  of heat flowed out from the gas

(b) 3.6×10³   cal of heat flowed into the gas

(c)  1.5×10⁴  cal of heat flowed into the gas

(d) 1.5×10⁴  cal of heat flowed out from the gas

Answer-a