Calculate the energy of a photon emitted by a hydrogen atom when the electron fa

Question

Calculate the energy of a photon emitted by a hydrogen atom when the electron falls from the n = 9 enenrgy level to the n = 4 energy level. Calculate the energy of a photon emitted by a hydrogen atom when the electron falls from the n=9 energy level to the n=4 energy level. 5.50 x 10-4 J 1.82 x 103 J 1.09 x 10-19 J 2.41 x 10-19 J 6.56 x 10-20 J A quintal is a historical unit of mass used in several countries. In France, a quintal is defined as 122 livres. There are 6.12 kg in 14 livres. You have 6.39 quintals of rice that have to be poured into cloth bags. Each cloth bag holds 25 pounds of rice. How many completely filled bags of rice can you get with this amount of rice? (1kg = 2.205 Ibs) 30.0 bags 764 bags 6.00 bags 159 bags 32.0 bags which atom would have the following ground state electron-configuration:

Explanation / Answer

16)

we know that

for hydorgen

En = -13.6/n2 eV

now

the energy difference is given by

E = E4 - E9

E = (-13.6 /16) - (-13.6/81)

E = -0.68 eV

now

1 eV = 1.6 x 10-19 J

so

E = -0.68 x 1.6 x 10-19

E = 1.09 x 10-9 J

so

the answer is option C

17)

now

given

mass = 6.39 quintals

now

1 quintal = 122 livres

so

mass = 6.39 x 122 livres

mass = 779.58 livres

now

1 livre = 6.12 /14 kg

so

mass = 779.58 x 6.12 / 14

mass = 340.788 kg

now

1 kg = 2.205 lb

so

mass = 340.788 x 2.205 lb

mass= 751.437 lb

now

1 bag can hold 25 lb

so

number of bags = mass / 25

= 751.437 / 25

= 30

so

20 bags can be filled

the answer is option A

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