MOST IMPORTANT SCIENCE FACTS FOR SSC CGL
1. What is the name of the scientist who stated that matter can be converted into energy? – Einstein
2. The isotopes of chlorine with mass number 35 and 37 exist in which ratio? – 3 : 1
3. A gas is found to have the formula (CO)n. Its vapour density is 70. What must the value of n be? – 5
4. Which law directly explains the law of conservation of mass? – Avogadro’s law
5. To whom the credit for the discovery of transuranic element goes? – Seaborg
6. How many moles are there is 140 g of Si (atomic mass of silicon is 28)? – 5
7. Which substance does not have a melting point? – Glass
8. By which a mixture of sand and naphthalene can be separated? – sublimation
9. An element X forms an oxide X03. What is the valency of X? – 6
10. Sodium carbonate crystals lose water molecules. What is this property called? – Efflorescence
11. By whom was the law of constant proportions enunciated? – Proust
12. What is the number of unpaired electrons in carbon atom? – 2
13. In an atom the order of filling up of the orbitals is governed by which principle? – Aufbau principle
14. Regarding the atom of a chemical element, magnetic quantum number refers? – Orientation
15. What are the atoms of the elements having same mass number but different atomic number called? – isobars
16. Rutherford’s scattering experiment related to the size of which thing? – nucleus
17. By whom was the absolute value of charge on electron determined? – R.A. Millikan
18. Which property of the elements is a whole number? – Atomic number
19. Discovery of the nucleus of an atom was due to the experiment carried out by which person? – Rutherford
20. What are the atoms of the elements which have same number of neutrons called? – Isotones
21. Whose experiment proved that the speed of light was always the same? – Michelson and Morley
22. Which element has two electrons in the K-shell only? – Helium
23. What is Electromagnetic radiation with maximum wavelength? – Radio waves
24. Which nuclear particles responsible for holding all nucleons together? – Mesons
25. In which process, a nucleus spontaneously breaks down by emitting radiation? – Radioactive decay
26. In atomic reactors, graphite is used as which name? – Moderator
27. Why is Cobalt-60 commonly used in radiation therapy? –Because it emits gamma rays
28. A radioactive substance has a half life of four months. Three-fourth of the substance would decay in howmany months? – 8 months
29. What is a bond formed by the transfer of electrons between atoms of the elements called? – ionic bond
30. What is a bond formed by sharing of electrons between atoms of the elements called? – covalent bond
31. What is the maximum number of hydrogen bonds in a H2O molecule? – 4
32. Select the compound in which chlorine shows oxidation state + 7? – HClO4
33. What is the oxidation of two Cl atoms in bleaching powder Ca(OCl) Cl? – +1,–1
34. What is the Oxidation state of Mn in acidic KMnO4 change from? – +7 to +2
35. Why is Molten NaCl good conductor of electricity? – Free ions
36. What is the common oxidation state of alkali metals in the combined state? – +1
37. What is the oxidation number and covalency-of sulphur in S8? – 0, 2
38. Starch iodide paper is used to test for the presence of which agent? – Oxidising agent
39. The pH of water at 25° C is 7. When it is heated to 100°C, what will the pH of water? – increases
40. When Metal carbonate reacts with dilute acids, what does it forms? – CO2
41. The element common to all the acids is known as which name? – Hydrogen
42. What is the sum of pH and pOH in aqueous solution at 25°C? – 14
43. By what factor is a solution with pH = 2 more acidic than one with pH = 6 ? – 104
44. Red litmus paper is changed into blue in solution of which thing? – Base
45. What is formed by dissolution of base or acid in water? – Exothermic
46. Blue litmus paper is converted into red in solution of which thing? – acid
47. According to Arrhenius theory of an acid and base, an acid is a substance that gives which ions in water? – H+ ions
48. What is the negative logarithmic value of hydrogen on called? – pH
49. What are the physical state of dispersion medium of a cloud ? – Gas
50. Vander Wall’s equation explains the behaviour of which gases? – real gases
1. What is the name of the scientist who stated that matter can be converted into energy? – Einstein
2. The isotopes of chlorine with mass number 35 and 37 exist in which ratio? – 3 : 1
3. A gas is found to have the formula (CO)n. Its vapour density is 70. What must the value of n be? – 5
4. Which law directly explains the law of conservation of mass? – Avogadro’s law
5. To whom the credit for the discovery of transuranic element goes? – Seaborg
6. How many moles are there is 140 g of Si (atomic mass of silicon is 28)? – 5
7. Which substance does not have a melting point? – Glass
8. By which a mixture of sand and naphthalene can be separated? – sublimation
9. An element X forms an oxide X03. What is the valency of X? – 6
10. Sodium carbonate crystals lose water molecules. What is this property called? – Efflorescence
11. By whom was the law of constant proportions enunciated? – Proust
12. What is the number of unpaired electrons in carbon atom? – 2
13. In an atom the order of filling up of the orbitals is governed by which principle? – Aufbau principle
14. Regarding the atom of a chemical element, magnetic quantum number refers? – Orientation
15. What are the atoms of the elements having same mass number but different atomic number called? – isobars
16. Rutherford’s scattering experiment related to the size of which thing? – nucleus
17. By whom was the absolute value of charge on electron determined? – R.A. Millikan
18. Which property of the elements is a whole number? – Atomic number
19. Discovery of the nucleus of an atom was due to the experiment carried out by which person? – Rutherford
20. What are the atoms of the elements which have same number of neutrons called? – Isotones
21. Whose experiment proved that the speed of light was always the same? – Michelson and Morley
22. Which element has two electrons in the K-shell only? – Helium
23. What is Electromagnetic radiation with maximum wavelength? – Radio waves
24. Which nuclear particles responsible for holding all nucleons together? – Mesons
25. In which process, a nucleus spontaneously breaks down by emitting radiation? – Radioactive decay
26. In atomic reactors, graphite is used as which name? – Moderator
27. Why is Cobalt-60 commonly used in radiation therapy? –Because it emits gamma rays
28. A radioactive substance has a half life of four months. Three-fourth of the substance would decay in howmany months? – 8 months
29. What is a bond formed by the transfer of electrons between atoms of the elements called? – ionic bond
30. What is a bond formed by sharing of electrons between atoms of the elements called? – covalent bond
31. What is the maximum number of hydrogen bonds in a H2O molecule? – 4
32. Select the compound in which chlorine shows oxidation state + 7? – HClO4
33. What is the oxidation of two Cl atoms in bleaching powder Ca(OCl) Cl? – +1,–1
34. What is the Oxidation state of Mn in acidic KMnO4 change from? – +7 to +2
35. Why is Molten NaCl good conductor of electricity? – Free ions
36. What is the common oxidation state of alkali metals in the combined state? – +1
37. What is the oxidation number and covalency-of sulphur in S8? – 0, 2
38. Starch iodide paper is used to test for the presence of which agent? – Oxidising agent
39. The pH of water at 25° C is 7. When it is heated to 100°C, what will the pH of water? – increases
40. When Metal carbonate reacts with dilute acids, what does it forms? – CO2
41. The element common to all the acids is known as which name? – Hydrogen
42. What is the sum of pH and pOH in aqueous solution at 25°C? – 14
43. By what factor is a solution with pH = 2 more acidic than one with pH = 6 ? – 104
44. Red litmus paper is changed into blue in solution of which thing? – Base
45. What is formed by dissolution of base or acid in water? – Exothermic
46. Blue litmus paper is converted into red in solution of which thing? – acid
47. According to Arrhenius theory of an acid and base, an acid is a substance that gives which ions in water? – H+ ions
48. What is the negative logarithmic value of hydrogen on called? – pH
49. What are the physical state of dispersion medium of a cloud ? – Gas
50. Vander Wall’s equation explains the behaviour of which gases? – real gases
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