PHY202: Modern Physics I TMA1 Question and answer

PHY202: Modern Physics I TMA1

Question 1 : Two hydrogen atoms have electrons in the n =3 energy level. One of the electrons jumps to the n = 2 level, while the other jumps to the n = 1. Which property is larger for the first photon?
A. velocity
B. frequency
C. wavelength
D. energy

ANSWER TO QUESTION IS D. Energy

When electron move from energy level to another, it mean it has gain energy which is high than the amount of energy it have, as such we said the atom is excited, but on loosen the energy the electron will fall back to lower energy level, the rate at which the electron fall depend on the amount of energy it lost, the higher the energy an atom lost the lower the energy level it fall.

So atom with n = 2 have higher energy level compare to atom with n = 1.

Question 2 : A gas can be identified by means of its spectral lines because each element
A. emits characteristic wavelengths when electrically excited
B. has different atomic mass
C. ocupies a unique position in the periodic table
D. can be recognized when greatly magnified

ANSWER TO QUSTION 2 IS A. emits characteristic wavelengths when electrically excited
spectrum have wavelength, and each of the atom has its own characteristic of wavelength as such, when they view with spectrophotometer, the atom can be identify by it wavelength

Question 3 : Calculate the wavelength in angstroms of electromagnetic radiation emitted by a hydrogen atom which undergoes a transition between energy levels of -1.36×10−19×10−19 J and ‘-5.45 ×10−19×10−19J. (Take Planck??s constant h = 6.6 ×10′−34×10′−34 Js)
A. 4884 A
B. 3646 A
C. 1215 A
D. 912 A

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Question 4 : What is another name for atomic number?
A. proton number
B. mass number
C. nucleon number
D. quanta

ANSWER TO QUESTION 4 IS A. proton number

Atom is made up of electron Neutron and Proton. Atom have nucleus that compose of proton and Neutron. Neutron is the sum of proton and electron in an atom the neutron give the atomic mass of an atom, why electron is the negative charge that revolve round the nucleus, and proton is the positive charge that equal the number of electron.

Question 5 : Which of the following is the correct electronic configuration of Sodium (Z = 11)
A. 2s22s22p62s2
B. 1s22s22p8
C. 1s22s12p63s2
D. 1s22s22p63s1

Answer to question 5 is D. D. 1s22s22p63s1

 

Sodium have atomic number of 11, it mean that the total number electron is 11.

Now can break it down in this way

1s is for the first orbit and it can only occupied, by 2 electron

2s is second orbit and is still s orbit so it cannot occupied more than 2 electron

2p is the third orbit, is a p orbital it have occupy maximum of 6 electron

3s is the fourth orbit is an s orbit so it can only occupy 2 electron

When eleven electron share among the orbit now we have 2, 2, 6, and 1

Mean 1s22s22p63s1

1s, 2s, 2p, and 3s, are orbital which the electron are share to according to Hunde Rules.

Question 6 : What is the shape of an atom?
A. spherical
B. rectangular
C. circular
D. round

The answer to question 6 is Spherical

Question 7 : Calculate the wavelength in nanometers of photons having an energy of 1.80 eV
A. 342 nm
B. 342 mn
C. 691 nm
D. 590 nm

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Question 8 : An electron in He+ is in an n = 2 orbit. According to Bohr’s theory, what is its magnetic moment due to its orbital motion?
A. $4.54\times{10^{-23} }J/T
B. 1.31×10−23J/T
C. 3.22×10−23J/T
D. 2.32×10−23J/T

 

Question 9 : The atomic number of calcium is 20. How many electrons do you expect to find in each shell of a calcium atom in its ground state?
A. 2, 4, 4, 2
B. 2, 8, 8,1
C. 2, 8, 8, 2
D. 2, 8, 0

Answer to question 9 is B. 2,8,8,1

Question 10 : If electrons in hydrogen atoms are excited to the fourth Bohr orbit, how many different frequencies of light may be emitted?
A. 1
B. 8
C. 3
D 6

If you have answer to question 3, question 7, question 8, and question 10, please drop as a comment this post thank you

 

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