20. The electron in a hydrogen atom, originally in level n-9, undergoes a transi
ID: 693381 • Letter: 2
Question
20. The electron in a hydrogen atom, originally in level n-9, undergoes a transition to a lower level by cmiting a photon of wavelength 384 nm. What is the final level ofthe electron? (e-3.00 x 108 m/s, h-6626x 1034 ,- 2.179 x 10-18 a. 2 b. 3 d. 18 21. Which of the following chemical equations does not correspond to a standard molar enthalpy of formation? b, Cis) + 12o,(g) CO(g) c, N2(g) + 02(g) 2 NOA) d.N2(g) + 202(g) N2Odg) 22. What is the wavelength of a photon that has an encrgy of 3,097 10 a. 3.1 x 1013 nm b.4.67 x 1037 0m . 6.42 x 1o-21 nm d. 9.29 x 1021 nm e. 6.16 x 10-12 m 23. The contribution for which de Broglie is best remembered in modern science is a. his statement that no clectron can have identical values for all four quantum numbers. b. his proposal that particles of matter should be associated with wavelike behavior c. his statement that an electron can exist in an atom only in discrete energy levels. d. his statement that elements show periodic repetition of properties. e. his statement that electrons occupy all the orbitals of a given sublevel singly before pairing begins. 24. Iron oxide reacts with aluminum in an exothermic reaction. re20,(s) + 2 Al(s) 2 Fe(s) + A1203(s) The reaction of 5.00 g Fe203 with excess Al(s) evolves 26.6 kJ of energy in the form of heat. Calculate the enthalpy change per mole of Fe O, reacted a. -5.32 kJ/mol b.-1.33 × 102 klinol c.-2.12 x 10 kJ/mol d.-212x102 kltnol e. -8.50 x 102 kJ/molExplanation / Answer
20.lamda = 384nm = 384*10^-7 cm
1/lamda = RH(1/n1^2- 1/n2^2)
n2 = 9
RH = 109678cm^-1
1/384*10^-7 = 109678(1/n1^2 -1/(9)^2)
26041.4 = 109678(1/n1^2 -1/81)
(1/n1^2 -1/81) = 26041.4/109678
1/n1^2 -0.01234) = 0.2374
1/n1^2 = 0.2374+0.01234
1/n1^2 = 0.24974
n1^2 = 1/0.24974
n1^2 = 4
n1 = 2
a. 2>>>>answer
21. b. C(s) + 1/2O2(g) ----------> Co(g)
22.All moving body have dual nature that means paritcal as well as wave nature.
b. his proposal that particle of matter should be associated with wavelike behavier.
24.no of moles of Fe2O3 = W/G.M.Wt
= 5/160 = 0.03125moles
energy = 26.6Kj
= 26.6KJ/0.03125 moles = -8.5*10^2 KJ/mole
e. -8.50*10^2 KJ/mole
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