Search This Blog

Theme images by Storman. Powered by Blogger.


Recent in Sports

Home Ads



Random Posts

Atoms and Molecules Viva Questions


1. What is the Avogadro number of Helium (He) atoms weigh ?

Ans: 4.0 g

2. Determine the number of hydrogen atoms in 3 mole of NH3 ?

Ans: 9 x 6.02 x 1023

3. Which of the following weighs least among  the following?

(a) 0.224 litres of O2 at NTP

(b) 6.02 x 1023 molecules of oxygen

(c) 6.02 x 1023 atoms of carbon

(d) 10 g of CO2

Ans: 0.224 litres of O2 at NTP

4. An element's oxides contain 57.1 % and 72.1 % oxygen, respectively. What is the second oxide if the first oxide is MO?

Ans: MO2

5. What is the molarity of Na2CO3 solution containing 10.6 g per 500 ml solution?

Ans:  0.2

6. Determine the volume of 0.5 M HNO3 that can be prepared from 25 mL of 2.5 M HNO3

Ans: 125 mL

7. If 30 L is converted into SI unit and expressed in scientific notation,  determine the value obtained?

Ans:  3 x 10-2 m3

8. The average density of earth is 5.5 g cm-3. In kg m-3, determine the average density?

Ans: 5.5 x 10-3

9.  In 1.0046, how many significant figures are there?

Ans:  five

10. From the given lists, which of the following has more number of rnolecules ?

(a) 1 g CO2

(b) 1 g N2

(c) 1 g H2

(d) 1 g CH4

Ans: 1 g H2

11. Carbon monoxide and carbon dioxide may be taken as examples for illustrating which  law ?

Ans: Law of multiple proportions

12. From the given, which of the following contains Avogadro number of atoms,

(a) 11.2 L of H2 at STP

(b) 32 g of oxygen

(c) 28 g nitrogen

(d) 22.4 L of Cl2 at STP

Ans: 11.2 L of H2 at STP

13. Find the volume of oxygen at STP required to react with 3 g graphite to give CO2  ?

Ans: 5.6 L

14. A solute has a molecular mass of 60 g and 90 g of it is dissolved in a litre of solution. Then what is its molarity?

Ans: 1.5

15. From the given samples, determine which of the following is not a mixture?

(a) air (b) milk (c) smoke (d) water

Ans: Water

16. The volume of l g of a gas at STP is 1.12 L. What will be its molecular mass ?

Ans: 20

17. A mass of 16 g of an element was mixed with 32 g oxygen when 32 g of compound was formed. If the element was the limiting reagent, what will be the mass ratio of the element to oxygen in the compound ?

Ans:  1:1

18. Chemical equations are balanced so that they are in accordance with which law?

Ans: Law of conservation of mass

19. At NTP, 0.225 g of carbon reacts with 140 mL of oxygen. What would the compound's molecular formula be then?

Ans: C3O2

20. 0.25 g of a tetratomic element is 3.125 x 10-3 mole. Then what is the atomic mass of the element is

Ans:  20

21. Neon contains two isotopes of atomic masses 20 and 22 in the mass ratio 9 : 1  respectively. Find the atomic mass of the element ?

Ans: 20.2

22. What is the atomicity of ozone?

Ans: The atomicity of ozone is 2

23. Determine which molecule from the following elements is tetratomic?

(a) ozone (b) phosphorus (c) sulphur (d) xenon

Ans: Phosphorus

24. What is the number of significant figures in 6.023 x 1023 ?

Ans: The number of significant figures is  4  

25. Determine the approximate number of atoms present in lg CH3COOH ?

Ans:  The approximate number of atoms present is 1022

26. Find the number of significant figures in 0.0480 ?

Ans: The number of significant figures is 3

27. Give the number of dimensionally independent physical quantities in SI units?

Ans: 7

28. Give the equivalent of 1 cm3 of volume?

Ans: 10-3 dm3

29. Determine the equivalent of one joule of energy ?

Ans:  0.2381 cal

30. From the following, determine the SI unit of work?

(a) cal (b) Joule (c) litre-atm (d) ergs

Ans: Joule


31. One kg weight is equivalent to

Ans:  9.8 N

32. The unit of J. Pa-I is equivalent to

Ans:  m3

33.  From the listed elements, determine which of the element is not an element?

(a) Diamond (b) 22 carat gold (c) graphite (d) oxygen

Ans: 22 carat gold

34.  From the given mixtures, find which one is not a homogeneous mixture?

(a) one rupee coin (b) gasoline (c) iodised table salt (d) air

Ans: Iodised table salt

35.  Give the mass of a Mg atom ?

Ans: The mass of Mg atom is 24.3/6.02 x 1023 g  

36.  Determine the number of mols of carbon present in 1 mot of ethanol?

Ans:  2

37. 615.00 has...........significant figures

Ans: 5

38. How will you measure the Luminous intensity ?

Ans: The luminous intensity is measured in terms of Candela

39. The prefix tera means

Ans: 1012

40. Pure water can be obtained from sea water by which process?

Ans:  Distillation process

41. From the listed elements, find which one contains the largest number of molecules?

(a) 1g CO2  (b) 1g N2 (c) 1 g H2  (d) 1 g CH4    

Ans:  1 g H2   

42. Carbon forms two oxides CO and CO2. This illustrates which law?

Ans: Law of  Multiple proportions

43. Two oxides of a metal contain 50% and 60% of oxygen respectively. If the formula of the first oxide is MO, determine the formula of the second one?

Ans: The formula of the second one is M2O3

44. What is the simplest formula for a compound with 50% of element X (atomic mass 10) and 50% of element Y (atomic mass 20) in it?

Ans: The simplest formula is: X2Y

45. Which of the following contains the same number of atoms as in 6 g carbon?

(a) 24 g Mg  (b) 23 g Sodium  (c) 20 g Ca  (d) 63.5 g Cu

Ans: 20 g Ca 

46. 3.2 g of gas contains 6.02 x 1022 molecules. determine its vapour density?

Ans: The vapour density is 16

47. Find the volume of 1 M NaOH required to convert 1.2 g of NaHSO4 completely to Na2SO4 ?

Ans: 10 ml

48. How many moles of water would be formed when 4 g of methane (CH4) are burnt?

Ans: 0.5

49. calculate the number of significant figures of the following numbers?

(a) 100.04   

Ans: 5

(b) 4.20 x 1010 

Ans: 3

(c) 324.0

Ans: 4

(d) 500.00

Ans: 5

(e) 0.02670 

Ans: 4

50. Compute the following:

(a) 5.28 x 0.156 x 3/0.428

Ans: 5.77

(b) 5.28 x 0.156 x 3/0.421

Ans: 5.67

51.  List the proper number of significant figures in the following and indicate which zeros are significant?

(a) 0.216

Ans: 3 Significant figures

(b) 90.1

Ans: 3 Significant figures and zero is significant

(c) 800.0

Ans: 4 Significant figures all zeros are significant

(d) 0.0670

Ans: 3 Significant figures, last zero is significant

52.  Determine the number of moles of Oxygen atoms are there in

(a) one mole of HNO3

Ans: 3 moles

(b) one mole of H2SO4

Ans: 4 moles

53. Determine the number of moles of water produced when 8 g of methane (CH4) are burnt?

Ans: 1 mol.

54. How many moles of KClO3 are needed to give 1.5 moles of oxygen?

Ans: 1 mol.

55. How many moles of KCl are formed when 0.33 mol of KClO3 is decomposed?

Ans: 0.33 mol.

56. A chemist weighs 10 g of water, 10 g of ammonia and 10 g of hydrogen chloride. Calculate the total number of moles contained in the mixture?

Ans: 1.4 moles

57. Give the mass of a silver atom?

Ans: 1.794 x 10-22

58. Determine the number of molecules contained in a drop of water weighing 0.04 g?

Ans: 1.34 x 1021 molecules

59. Express 0.000000367 in scientific notation and calculate the significant figures?

Ans: 3.67 x 10-7 ; Number of significant figures is 3

60. What is the mass of HCl required to neutralise completely 5g  of NaOH?

Ans: 4.545 g

61. Which contains more molecules: 1 g of sulphur dioxide or 1 g of sulphur trioxide?

Ans: 1 g of SO2

0 on: "Atoms and Molecules Viva Questions"