1) Which of the following(s)is /are correct? 1. Phosphoresence is a photoluminsseence process in which atoms or molecules are excited by absorption of electromagnetic radiation. The excited species then relax back to the ground state in 10^-8 seconds by giving up their excess energy as photons. II. The difference in absorption and emission wavelengths in fluorescence process is called a Stokes shift. III. Vibrational relaxation takes place during collisions between excited molecules and molecules of the solvent. A) Only I B) Only II C) I and II D) II and III E) I, II and III 2) List the following ionic species as electron donor in descending order. I- Ba^+2(E^circ Ba^2+/Ba_((s))=-2.906V II- Cd^+2(E^circ Cd^2+/Cd_((g))=-0.403V) III Co^+3(E^circ Co^3+/Co^2+=1.808V) IV -Cu^+2(E^circ Cu^2+/Cu_((s))=0.337V) A) Igt IIgt IIIgt IV 3) What is the difference between absorption and emission spectrum? A) An absorption spectrum is produced when atom release its excess amount of energy, while emission spectrum is produced when atom excited by EM radiation. B) An absorption spectrum is obtained by transmitting EM radiation through a substance, while an emission spectrum is spectrum of EM radiation that given off by a substance. C) An absorption spectrum is produced when atom excited by thermal energy source, while an emission spectrum is obtained when atom is stimulated by chemical energy. D) An absorption spectrum is obtained when excess energy of atom/molecule released as a thermal energy, whereas an emission spectrum is obtained when excess energy of atom/molecule released as a photon. 4) What is the oxidation number of Sulphur atom in Na_(2)S_(2)O_(3) (Na: 1 A group, O:6A group). A) -2 B) +4 C) +2 D) +3 E) -1

1) The correct answer is E) $I,\quad II$ and $III$. All three statements are correct. Phosphorescence is indeed a type of photoluminescence where atoms or molecules are excited by absorption of electromagnetic radiation, and then relax back to the ground state by emitting photons. The difference in absorption and emission wavelengths in fluorescence is called a Stokes shift. Vibrational relaxation does occur during collisions between excited molecules and solvent molecules.<br /><br />2) The correct answer is A) $I\gt II\gt III\gt IV$. The electron donor order is determined by the standard reduction potential. The higher the standard reduction potential, the better the species acts as an electron donor. In this case, $Ba^{+2}$ has the lowest standard reduction potential, making it the best electron donor, followed by $Cd^{+2}$, $Co^{+3}$, and $Cu^{+2}$.<br /><br />3) The correct answer is B) An absorption spectrum is obtained by transmitting EM radiation through a substance, while an emission spectrum is spectrum of EM radiation that given off by a substance. An absorption spectrum is produced when a substance absorbs specific wavelengths of electromagnetic radiation, while an emission spectrum is produced when a substance emits specific wavelengths of electromagnetic radiation.<br /><br />4) The correct answer is B) $+4$. The oxidation number of sulfur in $Na_{2}S_{2}O_{3}$ is +4. The oxidation number of sodium is +1, and the oxidation number of oxygen is -2. To find the oxidation number of sulfur, we can use the formula: $\text{Oxidation number of sulfur} = \frac{(\text{Total oxidation number of the compound}) - (\text{Oxidation number of sodium}) - 2(\text{Oxidation number of oxygen})}{2}$. Plugging in the values, we get: $\text{Oxidation number of sulfur} = \frac{(0) - (2) - 2(-2)}{2} = +4$.