Que: A thermodynamic system is considered to be an isolated one if (Engg Services-2011)

(a) Mass transfer and entropy change are zero
(b) Entropy change and energy transfer are zero
(c) Energy transfer and mass transfer are zero
(d) Mas transfer and volume change are zero

પ્રશ્ન: થર્મોડાયનેમિક સિસ્ટમ આઇસોલેટેડ ગણવામાં આવે છે જો
(a) માસ ટ્રાન્સફર અને એન્ત્રોપી  ફેરફાર શૂન્ય છે
(b) એન્ત્રોપી  ફેરફાર અને ઊર્જા ટ્રાન્સફર શૂન્ય છે
(c) ઊર્જા ટ્રાન્સફર અને માસ ટ્રાન્સફર શૂન્ય છે
(d) માસ ટ્રાન્સફર અને વોલ્યુમ ફેરફાર શૂન્ય છે

Ans: (c)
Explanation: A system is called isolated if there are no mass and energy transfer between system and surrounding,so answer is (c)

Que: Which one of the following represents open thermodynamic system?
A) manual ice cream freezer.
B) centrifugal pump.
C) pressure cooker.
D) bomb calorimeter.

Ans: B
Explanation: as we know in open thermodynamic system heat and mass across the boundary so in centrifugal pump both are acrosed when other option A. Ice cream freezer. C. Pressure cooker and D. Bomb calorimeter no mass are transfered, so ans is centrifugal pump.

Que: If I want to set a power plant in desert of 'Rajasthan' and I have option of
steam and gas power plant. Which plant I should set up?

Ans: Obviously gas because steam power plant work with steam that mean prime requirement is water and that unable to find in desert as our requirement whereas gas power plant consume gas as source and water requirement are too low, only use of water in gas power plant for cooling so gas power plant i prefer.

Que: How turbo charger works?

Ans: Turbo charger is used to compress the air which used generally in engine and when engine exhaust burned gases out it has more speed and temp so by using of its speed the small turbine are run then kinetic(speed) of this turbine are used to drive the compressor so air are compressed by that principle turbo charger work.

Que: What happens if gasoline
is used in a Diesel engine?
Diesel engine will work ?

Ans: No, It will not work,as the Compression ratio of Petrol engine is 6 to 10 & that of Diesel engine is 15 to 22. Thus on such high compression, gasoline gets highly compressed & it may blast.

Que: What happen if DIESEL used in PETROL engine?

Ans: This is not true. Diesel is much harder to ignite than petrol and relies on very high compression (5-10 times greater than a petrol engine) to superheat air in the cylinders and thus trigger ignition. Consequently the fuel is injected just prior to TDC (top dead center). Petrol is injected on the down stroke  compressed on the upstroke and burns when ignited by the spark plug.
Diesel contains much longer chain hydrocarbons and is much "heavier" and less volatile. It doesn't burn completely in the petrol engine resulting in smoking (when part of a fuel mixture) to complete non-running as the mixture is enriched.
Petrol introduced into a diesel engine burns immediately it is blown in and with the wrong dynamics, making the engine run badly and unevenly, potentially causing damage.

Que: What is TDC and BDC in internal combustion (IC) engine?

Ans:  TDC (top dead center) means the upper most position of piston in cylinder & BDC (bottom dead center) means maximum lower position of piston in IC engine.

Que: How fuel are burnt in major diesel engine and why not used spark plug?

Ans: Mostly Diesel are burnt in diesel engine by compression and so it is broadly known "CI-COMPRESSION IGNITION" engine. Burning of fuel are happen because of when piston moves up in close cylinder chamber it is compressed so as per law of boyle and charles temperature of air also increased at last when fuel are injected due to internal temperature of air it is burning.

Que: What says "Zeroth law of thermodynamics"?
Ans: