ECAT Chemistry Basic Concepts

1. A molecule ion is formed by

2. Who determined atomic masses of elements?

3. Mass spectrometer measures the

4. The relative atomic mass of chlorine is 35.5. What is the mass of 2 moles of chlorine gas?

5. Which of the following is not related to a.m.u?

6. Which of the following statements is correct for a chemical reaction?

7. Isotopes differ in the

8. Isotopes differ in:

9. A piece of paper is burnt in air, the gas produced is passed through distilled water. The pH of water will be

10. A pharmacist prepared 50 ml sample of a cough mixture. It was found that it has a mass of 46g. What is the density (g/ml) of this mixture? Stated to correct number of significant figures?

11. What is the correct relationship between empirical and molecular formulas?

12. All of the following statements are incorrect for 20 mol of hydrogen

13. Which of the following statements is not true?

14. The mass of 2 moles of sodium hydroxide will be

15. “A” compound always consists of the same elements combined in the same fixed ratio. “The statement is”

16. Empirical formula and formula unit of an ionic compound

17. The following statement contained in a student’s laboratory report is a conclusion

18. The number of moles of CO₂ which contain 8g of Oxygen?

19. An atom is:

20. Which of the following produced in the ionization of mass spectrometer?

21. The mass of one mole of electron

22. Which is the correct statement about limiting reactant?

23. One mole of SO₂ contains.

24. When energy is released during a reaction, it is

25. A compound has molar mass = 228.3g/mol. When it was analyzed by a scientist, It was found that it contains 30.68% nitrogen. How many nitrogen atoms are there in each molecule of dye?

26. A vessel contains 10g of N₂, 10g of H₂ and 10g O₂. Which one has the largest number of atoms?

27. Copper (II) oxide is mixed with organic compound during combustion. The purpose is:

28. Many elements have fractional atomic masses. The reason is that

29. The soul of chemistry is its dealing with

30. The empirical formula of the compound having 50% sulphur and 50% oxygen by mass is

31. The reaction? 4NH₃ + 3O₂ → 2N₂ + 6H₂O indicates that?

32. Which set of species has the same number of electrons?

33. A limiting reactant is the one which

34. 27g of Al reacts completely with how much mass of O₂ to produce Al₂O₃?

35. A ring contains 1.2g of diamond. How many number of carbon atoms re in diamond?

36. The relative abundance of the ion with a definite m/e value is measured by

37. Freezing point of a substance is a temperature of which a liquid substance is converted to solid. It is

38. A compound having the highest % age of oxygen by weight is?

39. The volume occupied by 1.4g of N₂ at S.T.P is

40. One cm³H₂ gas at S.T.P. contains number of atoms

41. Which of the following contains 3.01 x 10²² silver ions?

42. What will be the pressure of vapours as these are sent to the ionization chamber?

43. The number of molecules in 10Cm³ of chlorine gas at S.T.P. is

44. When the following reaction equations is properly balanced number of moles of O₂ will be:

45. What are the number of water molecules in 9g of water

46. What are the ratios among the volumes of gases of ³²O₂, ²H₂ and ¹⁶CH₄, if they taken in

47. Point out the element having atomic mass = 63.546

48. The compound having highest % age of oxygen is

49. The identity of an element is determined by

50. Choose the exact name of formula which is based on the actual molecule?