1) An ideal gas in a cylinder is compressed adiabatically to one -third of its original volume. A work of 45 J is done on the gas by the process. The change in internal energy of the gas and the heat flowed into the gas, respectively are A) 45 J and zero B) -45 J and zero C) 45 J and heat flows out the gas D) -45 J and heat flows into the gas Answer: Option AExplanation:For adiabatic process, △Q=0 Now, from first law of thermodynamics , we have △Q=△U+△W △W= -45 J or work done on the gas ⇒ 0=△U−45 ⇒ △U=45J