** Company: ** DRDO

DRDO Question Paper Dec 2010

1. The thermal conductivity k of a liquid metal is predicted via the empirical equation k = Aexp(B/T), where k is in Js-1m-1K-1 and T is absolute temperature in K. A and B are constants. The units of A and B are, respectively,

(A) Js-1m-1K-1 and K-1 (B) Js-1m-1K-1 and K

(C) J-1 smK and K-1 (D) J-1 smK and K

2. % Excess air for combustion process is defined as

(O2 entering the process-O2 required)

(A) % Excess air = ——————————————— x 100

O2 required

(O2 required – O2 entering the process)

(B) % Excess air = ————————————————– x 100

O2 entering the process

O2 required

(C) % Excess air = ———————————————- x 100

(O2 entering the process – O2 required)

O2 entering the process

(D) % Excess air = ——————————————————– x 100

(O2 required – O2 entering the process)

3. To prepare a solution of 50% sulfuric acid, a dilute waste acid containing 27% sulfuric acid is fortified with a fresh acid containing 96% sulfuric acid. The amount of fresh acid required for each 100 kg of dilute waste acid is

(A) 13.5 kg (B) 25 kg (C) 50 kg (D) 100 kg

4. A flue gas analysis gave 10% O2, 25% CO2 and 65% N2 at 160 °C and 760 mm Hg. The ratio of partial pressures of CO2 to O2 is equal to

(A) 1 (B) 2 (C) 2.5 (D) 4

5. In the extraction of nicotine from a nicotine-water solution by kerosene, the pressure and temperature are kept constant. The available degree(s) of freedom is/are

(A) 0 (B) 1 (C) 2 (D) 3

6. The hydrostatic equation of pressure P with height h of an incompressible fluid of density ? and specific weight ? is

(A) P = ?/h (B) P = ? / h

(C) P = ? h (D) P = ? h

7. A gas is being compressed from an enthalpy of 489 kJ/kg to 509 kJ/kg in a steady state open process. The entry and exit velocities of the gas are zero and 60 m/s, respectively. Assume that there is no heat loss or gain, no reaction, and potential energy change is negligible. If the load is 100 kg/h of gas, the work done on the gas is equal to

(A) 2000 kJ (B) 2180 kJ (C) 2500 kJ (D) 3000 kJ

8. The corresponding Maxwell relation for the Gibbsian equation dG = -SdT +VdP is

(A) (B)

(C) (D)

Statement for Linked Answer – Questions 9 and 10:

A system is taken from state A to state B along path ACB where 100 J of heat flows into the system and the system does 40 J of work.

9. How much heat flows into the system along path AEB if the work done by the system is 20 J?

(A) 20 J (B) 40 J (C) 60 J (D) 80 J

10. The system returns from B to A along path BDA. If the work done on the system is 30 J, what will be the amount of heat liberated/generated?

(A) -90 J (B) 90 J (C) 30 J (D) -30 J

11. Acentric factor for Argon is

(A) >1 (B) 1 (C) 0 (D) <>

12. Wet steam at 270 °C enters a throttling calorimeter with enthalpies of 1200 kJ/kg and 2800 kJ/kg in liquid and gas phase, respectively. It leaves as supersaturated steam at 0.1 MPa and 120 °C with an enthalpy of 2700 kJ/kg. The quality of steam is

(A) 14/16 (B) 13/16 (C) 15/16 (D) 27/40

13. Superheated steam at 3 MPa and 300°C having enthalpy of 3000 kJ/kg enters a turbine at the rate of 1 kg/sec and leaves as dry saturated steam at 60 °C with an enthalpy of 2600 kJ/kg. If kinetic and potential energy changes are ignored, the power output of the turbine is

(A) 400 kW (B) 5600 kW (C) 3000 kW (D) 2600 kW

Statement for Linked Answer – Questions 14 and 15:

A reversible heat engine absorbs 800 kJ as heat from a reservoir at 600 K and rejects 100 kJ energy as heat to a reservoir at 300 K, as shown in the following figure.

14. The heat interaction (Q) with reservoir at 400 K is

(A) – 600 kJ (B) 400 kJ (C) – 400 kJ (D) 600 kJ

15. The work done (W) by the engine is

(A) 500 kJ (B) 400 kJ (C) 350 kJ (D) 300 kJ

16. The partial volume of component A in a binary mixture (A – B) is 60 x 10-6 m3/mol. The mole% of A in the mixture is 60%. The density of the mixture is 760 kg/m3. What will be the partial volume (m3/mol) of B in the mixture?

(Given: Molar mass of A is 50 x 10-3 kg/mol; molar mass of B is 20 x 10-3 kg/mol)

(A) 30 x 10-6 (B) 35 x 10-6 (C) 40 x 10-6 (D) 60 x 10-6

17. The enthalpy of vaporization of water at 100 °C is 2300 kJ/kg. The isobaric heat capacities of liquid and vapor are, respectively, 4.0 kJ/kg-K and 2 kJ/kg-K. The enthalpy of vaporization at 150 °C will be

(A) 2400 kJ/kg (B) 2100 kJ/kg (C) 2500 kJ/kg (D) 2200 kJ/kg

18. The following equations have been proposed for an isothermal binary solution where the standard states are the pure components at the solution temperature and pressure:

?1 = Ax1; ?2 = Bx2

What can be said about the above relation?

(A) It satisfies Gibbs-Duhem equation

(B) It does not satisfy Gibbs-Duhem equation

(C) It is thermodynamically consistent

(D) It satisfies both (A) and (C)

19. The enthalpy change of some reactions are given below:

CO (g) + O2 (g) ? CO2 (g) ?H = -300 kJ

H2 (g) + O2 (g) ? H2O (1) ?H = -320 kJ

H2O(1) H2O(g) ?H = 50 kJ

What will be the enthalpy change for the following reaction:

CO(g) + H2O(g) à CO2 (g) + H2 (g)

(A) -70 kJ (B) 30 kJ (C) -30 kJ (D) 70 kJ

20. The decrease in the Helmholtz Free Energy for system in a given process for which initial and final temperatures are equal to the surrounding temperature indicates.

(A) Maximum work obtained from the system

(B) Minimum work obtained from the system

(C) Minimum work which can be done on the system

(D) Both (A) and (C)

21. The vapor pressures of benzene and toluene at 70 °C are 4 and 6 atm, respectively. A liquid feed of 0.6 moles of toluene at the same temperature is vaporized. Assuming Raoult’s law, the vapor phase mole fraction of benzene at equilibrium is approximately.

(A) 0.30 (B) 0.40 (C) 0.50 (D) 0.60

22. An oil film of viscosity u and thickness h is sheared between a solid stationary wall and a circular disc of radius R, where h < <> The circular disc is rotating with angular speed w. For the same thickness of the film, if the radius of the disc is doubled, the angular speed remaining the same, by what factor the torque on the disc increases?

(A) 2 (B) 4 (C) 8 (D) 16

23. A circular fire hose of inner cross-sectional area 100 cm2 is connected to a nozzle whose exit cross-sectional area is 4 cm2. The horizontal nozzle is discharging water at 0.6 m3/minute to the atmosphere. If a pressure gauge is connected to the hose side just before the nozzle, what would be the reading of the pressure gauge?(Density of water = 1000 kg/m3 )

(A) 312 kPa (B) 624 kPa (C) 89 kPa (D) 178 kPa

24. A reciprocating pump has a piston of cross-sectional area A and is connected to a crank of radius r which is rotating with angular velocity ?. The pump is connected to the suction and the delivery pipes whose internal cross-sectional area is A1. The maximum velocity of the fluid element in the suction or delivery pipe is

(A) (B) (C) ?r (D)

25. Assuming that the thrust T of a propeller depends upon the diameter D, speed of advance V, angular velocity ?, dynamic viscosity µ, and density ?, which of the following dimensionless parameters can be derived by dimensionless analysis?

(1) (2) (3) (4)

Select the correct answer using the codes given below:

(A) 1, 2 and 3 (B) 1, 3 and 4 (C) 2, 3 and 4 (D) 1, 2 and 4