As you are preparing of the Placement Drive of the ONGC let me tell you that In General the Procedure of the Placement Drive Consist if three Rounda that are :
Aptitude test
Group Discussion
Interview

the Aptitude test paper of the ONGC Palcement Drive is given below

1. Sherwood Number Is the ratio of? Convective Mass transfer coefficient to Diffusive Mass transfer coefficient. ( Sh = KL/D)

2. Catalyst in the manufacture of HNO3? Pt-Rh catalyst

3. Process used to convert Black liquor to white liquor? ANS:

4. What is Capitalised cost?

5. Which type of agitator will be used for viscous liquids?

6. Cavitation in pumps can be avoided by? Maintaining high vapour pressure.

7. What is Bode Criteria? A feedback control system is unstable if amplitude ratio of corresponding open loop transfer function is larger than 1 at the cross over frequency.

8. After absorption of Ammonia in water how it can be recovered?

9. According to Collision theory How “T” and “K” are related? K proportional to T^1/2

10. Which law gives about the generation of EMF?

11. What is the Change in entropy in mixing two components?

12. Glass etching can be done by using?

13. What is Plancks law, Kirchoffs law and Stefan boltzman law ?

14. What is the reason for not using saturated steam in evaporator?

15. Order of reaction for which the size of MFR is bigger than PFR?

16. How optimum reflux ratio can be chosen?

17. For gaseous reactions which reactor will give best result?

18. Penetration theory in Mass transfer?

19. What is the maximum allowable pressure drop on tube side in shell and tube heat exchangers?

20. For exothermic reactions as the temperature decreased ,how rate of reaction changes?

21. Corner Frequency corresponds to angle?

22. During Condensation which property does not change?

23. If Pr>1, then heat transfer confined to? Viscous sub layer

24. Minimum offset and oscillation occur with which type of controller?

25. Head developed by a pump depends on?

26. In cooling towers efficiency can be increased by ?

27. Ultrafine grinding uses which mechanism?

28. Composition of synthesis gas?

29. Aniline point of diesel shows?

30. Three unequal sized mixed flow reactors of volume 5L, 10L, 15L are arranged in which order for reactions of order n>0?

31. For natural convection Nusselt number is the function of?

32. Which mechanism is used in Fluid energy mill?

33. Film coefficient of heat transfer defined as?

34. Petroleum coke is made by residue by which process?

35. Chemical used in the test of COD?

36. Product of reaction between acetylene and chlorine?

37. For first order reactions, if thiele modulus is 10, then effectiveness factor is? 0.1

38. Graph between 1/C0 vs t is straight for reactions of order? 2

39. Which type of arrangement used for cold and viscous feed? Backward feed

40. Superheated steam is not used in evaporator dur to? Low heat transfer coefficient

41. Byproduct in the production of phosphoric acid ? Gypsum

42. The equivalent diameter for flow through rectangular duct of width B and Height H is? 2(BH)/(B+H)

43. What is dead time in process control?