Which of the following frequencies of electromagnetic radiation has the longest

Question

Which of the following frequencies of electromagnetic radiation has the longest wavelength? For potassium metal, the work function phi (the minimum energy needed to eject an electron from the metal surface) is 3 68e-19 J Which is the longest wavelength of the following which could excite photoelectrons? According to the Bohr theory of the hydrogen atom, the minimum energy (in J) needed to ionize a hydrogen atom from the n = 2 is Which of the following is a correct set of quantum numbers for an electron in a 3d orbital? Select the correct set of quantum numbers (n, I, ml, ms) for the highest energy electron in the ground state of potassium, K. The electronic structure 1s2 2s2 2p6 3s2 3p6 4s2 3d8 refers to the ground state of How many valence electrons are there in an atom with the electron configuration [ noble gas ]ns2 (n - 1 )d10np3? Which of the following element has the largest atomic size? Which of the following elements has the largest second ionization energy (IE2)? Which of the following contains covalent bonds? Using the bond energies provided below. calculate Delta H+ for the reaction Bond energies C - M = 413 kJ / mol. CI - Cl = 243 kJ / mol ; C - Cl = 339 kJ/mol ; H - Cl = 427 kJ / mol.

Explanation / Answer

1)

we know that

for a electromagnetic radiation

wavelength = speed of light / frequency

so

lesser the frequency , longer the wavelength

now

kilo = 10^3

       tera = 10^12

       giga = 10^9

       mega = 10^6

So the longest wavelength is that of 1 kilohertz

So the answer is option A) 1 kilohertz

Note : there is no such unit called bighertz

2)

we know that

work function = h x c / lamda

where

h = plancks constant

given

E= 3.68 x 10-19

so

3.68 x 10-19 = 6.626 x 10-34 x 3 x 10^8 / lamda

lamda = 5.4 x 10-7 m

lamda = 540 x 10-9 m

lamda = 540 nm

so

the longest wavelength is 550 nm

So the answer is option A) 550 nm

3)

for hydrogen

En= (-13.6 / n2 ) eV

so

for

n=2

E2 - -13.6 / 4

E2 = -3.4 eV

now

ionization energy E= Einfinity - En

for

n=2

E= 0 - (-3.4)

E= 3.4 eV

we know that

1 eV = 1.6 x 10-19 J

so

E = 3.4 x 1.6 x 10-19 J

E= 5.44 x 10-19 J

so the minium energy required (ionization potential ) is 5.45 x 10-19 J

so the answer is option D) 5.45 x 10-19 J

4) the rules to follow for quantum numbers are

     i) the values of l ranges from 0 to n-1

     ii) the values of m ranges from -l to +l

using these points

the correct answer is option D) n=3 ,l=2 , m=-2

5) the ground state electronic configuration of potassium is

     1s2 2s2 2sp6 3s2 sp6 4s1

So the highest energy electron resides in 4s1

For 4s1

n= 4

for S orbital l =0 , m= 0

spin quantum number is +1/2

so

the answer is option D) 4 , 0 , 0 , +1/2

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