TS 10th Class Physical Science Bits Chapter 6 Structure of Atom

These TS 10th Class Physical Science Bits with Answers Chapter 6 Structure of Atom will help students to enhance their time management skills.

TS 10th Class Physical Science Bits Chapter 6 Structure of Atom

Question 1.
Total number of orbitals associated with third shell is ( )
(A) 2
(B) 4
(C) 9
(D) 3
Answer:
(D) 3

Question 2.
Which of the following orbitals has least energy? ( )
(A) K
(B) L
(C) M
(D) N
Answer:
(A) K

Question 3.
How many elliptical orbits are possible for a given n=6? ( )
(A) 3
(B) 4
(C) 5
(D) 7
Answer:
(C) 5

Question 4.
Bohr atomic model explains the spectrum of …………………… . ( )
(A) He
(B) Li
(C) H
(D) all
Answer:
(D) all

Question 5.
Which of the following orbital has highest energy? ( )
(A) 3p
(B) 4s
(C) 3d
(D) 4p
Answer:
(D) 4p

Question 6.
The maximum number of unpaired electrons which can exist in an orbital according to Paulis exclusion principle. ( )
(A) 1
(B) 2
(C) 3
(D) many
Answer:
(A) 1

Question 7.
If n=4, the total number of p orbitaIs is : ( )
(A) 3
(B) 6
(C) 9
(D) 12
Answer:
(D) 12

Question 8.
The property possessed by the p orbitals: ( )
(A) no orientation
(B) spherical
(C) five degenerate orbitals
(D) has three orientations
Answer:
(D) has three orientations

Question 9.
The number of ‘s’ electrons in sodium atom Is ( )
(A) 5
(B) 10
(C) 6
(D) 11
Answer:
(A) 5

Question 10.
The maximum number of electrons that can be present In d subshell 🙁 )
(A) 2
(B) 6
(C) 10
(D) 14
Answer:
(C) 10

Question 11.
The sub-shell that is not present in ‘L’ orbit ( )
(A) s
(B) p
(C) d
(D) all of these
Answer:
(C) d

Question 12.
The quantum numbers n,l, m, m_s respectively of the electron 3d’ are ( )
(A) 4, 1, 0, -1/2
(B) 4, 0, -1, +1/2
(C) 3, 2, 0, +½
(D) 3, 1, 1, +1/2
Answer:
(C) 3, 2, 0, +½

Question 13.
Bohr’s atomic theory tells about the following : ( )
(A) quantum numbers
(B) energy levels
(C) sub energy levels
(D) shapes of orbitals
Answer:
(B) energy levels

Question 14.
The electronic configuration that contradicts the Aufbau principle among the following …………………. . ( )

Answer:

Question 15.
The total number of orbitals present In N the orbit.
(A) 2×4
(B) 4
(C) 4²
(D) 2×4²
Answer:
(C) 4²

Question 16.
The distance between the nucleus and the outermost orbital Is called
(A) electron affinity
(B) atomic radius
(C) bond length
(D) mean radius
Answer:
(B) atomic radius

Question 17.
The property that is indicated by principal quantum number
(A) size of main shell
(B) energy of shell
(C) A&B
(D) shape of orbit
Answer:
(C) A&B

Question 18.
The shape of p orbItal is ( )
(A) dumbbell
(B) spherical
(C) elliptical
(D) double dumbbell
Answer:
(A) dumbbell

Question 19.
Bohr’s atomic model can explain the structure of: ( )
(A) H⁺
(B) He⁺
(C) Li⁺
(D) H₂
Answer:
(B) He⁺

Question 20.
The quantum numbers of 2p electron are : ( )
(A) n=2; l=0
(B) n=2;l=3
(C) n=2; l=4
(D) n=2; l=1
Answer:
(D) n=2; l=1

Question 21.
In 1s²2s²2p⁴ the number of unpaired electrons in ground state are ( )
(A) 4
(B) 3
(C) 2
(D) 1
Answer:
(C) 2

Question 22.
The orbital which is very close to the nudes. ( )
(A) 6p
(B) 5s
(C) 5d
(D) 4f
Answer:
(D) 4f

Question 23.
The value of Planck’s constant is ( )
(A) 6.626 x 10³⁴ is
(B) 6.626 x 10^-34 is
(C) 6.02 x 10¹² is
(D) 6.062 x 10^-27 is
Answer:
(B) 6.626 x 10^-34 is

Question 24.
The maximum number of electrons, that can occupy ‘f’ sub-shell is ( )
(A) 10
(B) 6
(C) 12
(D) 14
Answer:
(D) 14

Question 25.
“The lowest-energy orbitals are filled up first”. This is called ( )
(A) Aufbau principle
(B) Pauli’s exclusion principle
(C) Hund’s rule
(D) Sommerfeld’s principle
Answer:
(A) Aufbau principle

Question 26.
The space around the nucleus where the probability of finding an electron is maximum is called: ( )
(A) region
(B) orbital
(C) quanta
(D) none of these
Answer:
(B) orbital

Question 27.
Identify n=2; l=0 ( )
(A) 2p
(B) 2d
(C) 2f
(D) 2s
Answer:
(D) 2s

Question 28.
The element whose electronic configuration is 1s²2s²2p⁵ is ( )
(A) nitrogen
(B) fluorine
(C) chlorine
(D) oxygen
Answer:
(B) fluorine

Question 29.
If the distance of an orbit from the nucleus increases, then the energy of the orbit. ( )
(A) decreases
(B) remains constant
(C) increases
(D) may increase or decrease
Answer:
(C) increases

Question 30.
The values of spin quantum numbers are (m1) ( )
(A)+1, -1
(B) +1/2, -1
(C) -1, -1/2
(D) +1/2, -½
Answer:
(D) +1/2, -½

Question 31.
After filling up ‘4s’ orbital the electron enters: ( )
(A) 4p
(B) 3d
(C) 5s
(D) 4f
Answer:
(B) 3d

Question 32.
For carbon atom (z=6) the 6th electron goes Into: ( )
(A) 3s
(B) 2d
(C) 2p
(D) 4s
Answer:
(C) 2p

Question 33.
The number of orbitals In 4d subshell is ( )
(A) 3
(B) 7
(C) 5
(D) 2
Answer:
(C) 5

Question 34.
The sub-atomic particles that revolve around the nucleus ( )
(A) protons
(B) electrons
(C) photons
(D) neutrons
Answer:
(B) electrons

Question 35.
The charge on a neutron is
(A) +1
(B) -1
(C) 0
(D) +2
Answer:
(C) 0

Question 36.
The shape of is orbital is ( )
(A) dumbbell
(B) double dumbbell
(C) cylindrical
(D) spherical
Answer:
(D) spherical

Question 37.
The principle which indicates that nitrogen atom has three unpaired electrons ; ( )
(A) Aufbau principle
(B) Somerfeld’s principle
(C) Pauii’s exclusion principle
(D) Hund’s rule
Answer:
(D) Hund’s rule

Question 38.
The number of orbitals present in n=3 is ( )
(A) 1
(B) 3
(C) 5
(D) 7
Answer:
(B) 3

Question 39.
Among the following which orbital has least energy? ( )
(A) 4s
(B) 3p
(C) 3d
(D) 4p
Answer:
(B) 3p

Question 40.
The l value of d subshell is: ( )
(A) 0
(B) 1
(C) 2
(D) 3
Answer:
(C) 2

Question 41.
The clock-wise spin of electron is represented by : ( )
(A) →
(B) ←
(C) ↑
(D) ↓
Answer:
(C) ↑

Question 42.
Shape of ’d’ orbital is:
(A) double-dumbell
(B) pyramidal
(C) spherical
(D) dumb-bell
Answer:
(A) double-dumbell

Question 43.
The number of m, values for I = 3 is
(A) 3
(B) 5
(C) 7
(D) 9
Answer:
(C) 7

Question 44.
[Ar] 4s² is the electronic configuration of …………………… . ( )
(A) Mg
(B) Be
(C) Ca
(D) Sr
Answer:
(C) Ca

Question 45.
Which of the following shells has highest energy. ( )
(A)K
(B) L
(C) M
(D) N
Answer:
(D) N

Question 46.
Bohr’s theory is valid for: ( )
(A) all atoms
(B) all molecules
(C) any atom or Ion having one electron
(D) all molecules
Answer:
(C) any atom or Ion having one electron

Question 47.
The sub-shells present in L shell are ( )
(A) s and d
(B) s and p
(C) s, p and d
(D) s, p, d and f
Answer:
(B) s and p

Question 48.
‘f’ orbitais are present In …………………… . ( )
(A) K-shell
(B) L-shell
(C) M-shell
(D) N-shell
Answer:
(D) N-shell

Question 49.
The following sub-atomic particles are known as numerous ( )
(A) protons + neutrons
(B) protocis+ positrons
(C) protons + electrons
(D) electrons + neutrons
Answer:
(A) protons + neutrons

Question 50.
The electronic configuration of copper is ( )
(A) [Ar]4s¹3d⁸
(B) [Ar]4s¹3d¹⁰
(C) [Ar]4s²3d⁸
(D) [Ar]4s²3d¹⁰
Answer:
(B) [Ar]4s¹3d¹⁰

Question 51.
Neutral particle present in an atom is ( )
(A) proton
(B) neutron
(C) electron
(D) positron
Answer:
(B) neutron

Question 52.
Orbitals having equal energies are called ( )
(A) valence orbitals
(B) empty orbitals
(C) overlapping shells
(D) degenerate orbitals
Answer:
(D) degenerate orbitals

Question 53.
Magnetic quantum number is related to ( )
(A) size
(B) shape
(C) orientation
(D) spin
Answer:
(C) orientation

Question 54.
The orbital whose l value Is ‘0’ Is designated as ………………… ( )
(A) s orbital
(B) p orbital
(C) d orbital
(D) f orbital
Answer:
(A) s orbital

Question 55.
Bohr’s model could not account for …………………………. . ( )
(A) Raman’s effect
(B) See back’s effect
(C) Condensation effect
(D) Zeeman’s effect
Answer:
(D) Zeeman’s effect

Question 56.
By removing or adding an electron to an atom, It becomes a / an ( )
(A) ion
(B) radical
(C) neutron
(D) gel
Answer:
(A) ion

Question 57.
Number of electrons that can be accommodated in f sub-shell is ( )
(A) 2
(B) 8
(C) 32
(D) 14
Answer:
(D) 14

Question 58.
Orbital without any directional character ( )
(A) s
(B) p
(C) d
(D) f
Answer:
(A) s

Question 59.
The electron after filling 5d sublevel enters ( )
(A) 5f
(B) 6p
(C) 6d
(D) 4g
Answer:
(B) 6p

Question 60.
The number of electrons present in M shell of aluminium atom : ( )
(A) 1
(B) 2
(C) 3
(D) 5
Answer:
(C) 3

Question 61.
The number of electrons present in (Cl^–) is ( )
(A) 17
(B) 18
(C) 16
(D) 10
Answer:
(B) 18

Question 62.
By losing an electron a neutral sodium atom becomes : ( )
(A) cation
(B) anion
(C) radical
(D) none of these
Answer:
(A) cation

Question 63.
According to Bohr’s theory, the angular momentum of an electron in 4th orbit is : ()
(A) 16 \(\frac{\mathrm{h}}{\pi} \)
(B) 4 \(\frac{\mathrm{h}}{\pi} \)
(C) 2 \(\frac{\mathrm{h}}{\pi} \)
(D) \(\frac{\mathrm{h}}{4 \pi}\)
Answer:
(C) 2 \(\frac{\mathrm{h}}{\pi} \)

Question 64.
Increase in the value of principal quantum number (n) indicates increase of ……………….. . ( )
(A) activity
(B) energy
(C) charge
(D) none
Answer:
(B) energy

Question 65.
The ‘l’ value for ‘f’ subshell Is ( )
(A) 1
(B) 2
(C) 3
(D) 4
Answer:
(D) 4

Question 66.
Number of orbitals for the sub she 3d is ( )
(A) 5
(B) 7
(C) 3
(D) 1
Answer:
(A) 5

Question 67.
The spin quantum number is denoted b ( )
(A) n
(B) m_l
(C) l₃
(D) m₅
Answer:
(D) m₅

Question 68.
The shorthand notation of electronic configurations ……………………. . ( )
(A) nl^x
(B) xlⁿ
(C) xn^l
(D) lxⁿ
Answer:
(A) nl^x

Question 69.
The maximum number of electrons that an orbital can hold is ( )
(A) 1
(B) 2
(C) 4
(D) many
Answer:
(B) 2

Question 70.
If the frequency of light wave (v) and Its wave length Is (λ), then speed of light c = ( )
(A) v/λ
(B) λ/v
(C) λv²
(D) vλ
Answer:
(D) vλ

Question 71.
electron gains energy by ……………………….. a particular frequency of light. ( )
(A) emitting
(B) absorbing
(C) producing
(D) exchanging
Answer:
(B) absorbing

Question 72.
Splitting of spectral lines In the presence of electronic field is called ( )
(A) Zeeman
(B) stark
(C) dispersion
(D) none of these
Answer:
(B) stark

Question 73.
The value of the electron which spins In clockwise direction is ………………………. ( )
(A) 1
(B) -1
(C) \(\frac{1}{2}\)
(D) \(\frac{-1}{2}\)
Answer:
(C) \(\frac{1}{2}\)

Question 74.
The minimum value of n is ( )
(A) 0
(B) 1
(C) -1
(D) -2
Answer:
(B) 1

Question 75.
M orbital can hold a maximum of …………… electrons. ( )
(A) 4
(B) 6
(C) 2
(D) 8
Answer:
(C) 2

Question 76.
Quantum theory was originated by ……………….. . ( )
(A) Bohr
(B) Helsenberg
(C) Plank
(D) Sommer field
Answer:
(C) Plank

Question 77.
each subshell holds maximum of electrons _______ ( )
(A) 2(2l+1)
(B) 2l+1
(C) l+1
(D) 2(2l+2)
Answer:
(A) 2(2l+1)

Question 78.
Name of the orbital for l= 1 is ( )
(A) s
(B) p
(C) d
(D) f
Answer:
(D) f

Question 79.
Splitting of spectral lines In electric field is known as ( )
(A) Zeemari effect
(B) Stark effect
(C) Photoelectric effect
(D) None
Answer:
(B) Stark effect

Question 80.
Splitting of spectral lines in magnetic field is known as …………………. . ( )
(A) Zeeman effect
(B) Stark effect
(C) Photoelectric effect
(D) None
Answer:
(A) Zeeman effect

Question 81.
If n=3, the main shell is ……………………… . ( )
(A) K
(B) N
(C) O
(D) M
Answer:
(D) M

Question 82.
For a given value of the number of integer values of m are …………………. . ( )
(A) l-1
(B) l+1
(C) 2l+1
(D) 2l-1
Answer:
(C) 2l+1

Question 83.
Which of the following is not a correct set of quantum numbers? ( )
(A) n=1, =0, m=0, m= -½
(B) n=2, 1=1, m=0, m1= +½
(C) n=0, 1=0, m = 0, m = +½
(D) n=3, =1, m=0, m= +½
Answer:
(C) n=0, 1=0, m = 0, m = +½

Question 84.
Which is the correct orbital designation for the electron with the quantum numbers
n=4, l=3, m=2, m_s=½? ( )
(A) 5p
(B) 3s
(C) 6s
(D) 4f
Answer:
(D) 4f

Question 85.
Which of the following is correct with respect to d-orbital? ( )
(A) spherical
(B) strong directional characters
(C) fivefold degenerate
(D) no directional character
Answer:
(C) fivefold degenerate

Question 86.
Which of the following is not correct? ( )
(A) 2p⁶
(B) 3s¹
(C) 2d⁵
(D) 4f¹²
Answer:
(C) 2d⁵

Question 87.
Which of the following electronic configuration corresponds to an inert gas? ()
(A) 1s² 2s²2p⁵
(B) 1s² 2s² 2p⁶
(C) 1s² 2s² 2p⁶3s¹
(D) None of these
Answer:
(B) 1s² 2s² 2p⁶

Question 88.
In which of the following Aufbau principle is violated? ( )
(A) 1s² 2s² 2p⁶ 3s² 3p¹
(B) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
(C) 1s² 2s² 2p⁶ 3s¹ 3p⁶ 4s² 3d¹
(D) 1s² 2s² 2p⁶ 3s² 3p⁶ 3d²
Answer:
(D) 1s² 2s² 2p⁶ 3s² 3p⁶ 3d²

Question 89.
The magnetic quantum number (m) for the outermost electron in sodium atom is ()
(A) 0
(B) +1
(C) -1
(D) -2
Answer:
(A) 0

Question 90.
When the 4p orbital In any atom are filled completely, the next electron goes to ( )
(A) 5s
(B) 3d
(C) 4d
(D) 4f
Answer:
(A) 5s

Question 91.
The n+ l value of 3d orbital is ( )
(A) 4
(B) 3
(C) 5
(D) 6
Answer:
(C) 5

Question 92.
………………………… waves are produced when an electric charge vibrates. ( )
(A) No
(B) Mechanical
(C) Electromagnetic
(D) None of these
Answer:
(C) Electromagnetic

Question 93.
The orbit of least energy ……………………….. . ( )
(A) K
(B) L
(C) M
(D) N
Answer:
(A) K

Question 94.
The maximum value of l for n = 5 is …………………….. . ( )
(A) 5
(B) 3
(C) -5
(D) 4
Answer:
(D) 4

Question 95.
………………………. colour of visible spectrum has highest wavelength. ( )
(A) red
(B) blue
(C) green
(D) violet
Answer:
(A) red

Question 96.
When an electron jumps from higher energy state to lower energy state it energy. ( )
(A) emits
(B) absorbs
(C) neither emits nor absorbs
(D) none of these
Answer:
(A) emits

Question 97.
A Quantum mechanical model of an atom was developed ( )
(A) Neils Bohr
(B) De Broglie
(C) Heisenberg
(D) Erwin Schrodinger
Answer:
(C) Heisenberg

Question 98.
Orbital quantum gives ………………………….. . ( )
(A) shape or orbital
(B) size and energy of orbital
(C) orientation of orbital
(D) spin of electrons
Answer:
(A) shape or orbital

Question 99.
Noble gases belongs to group …………………. . ( )
(A) VA
(B) VI A
(C) VII A
(D) VIII A
Answer:
(D) VIII A

Question 100.
The clockwise spin of electron is denoted by ………………….. . ( )
(A) →
(B) ←
(C) ↑
(D) ↓
Answer:
(C) ↑

Question 101.
The wavelength range of visible spectrum is …………………. . ( )
(A) 400 nm – 500 nm
(B) 400 nm – 600 nm
(C) 400 nm – 700 nm
(D) 500 nm – 700 nm
Answer:
(C) 400 nm – 700 nm

Question 102.
As ‘n’ increases size of the orbital ………………….. . ( )
(A) increases
(B) decreases
(C) does not change
(D) none of these
Answer:
(A) increases

Question 103.
For ‘l’ the minimum value is …………………………. and the maximum value is ………………….. . ( )
(A) 0, ¥
(B) 1, (n-1)
(C) 0, (n-1)
(D) -l to+l
Answer:
(C) 0, (n-1)

Question 104.
The value of rn1’ for an electron spinning in clock-wise direction is ……………… and for anti-clockwise direction is ………………………. . ( )
(A) -½, +½
(B) ½, ½
(C) 0, ½
(D) +½, -½
Answer:
(D) +½, -½

Question 105.
The order of colours in a rainbow are ……………………… . ( )
(A) ROYGBIV
(B) VIBGYOR
(C) VBGYIOR
(D) VIBYOGR
Answer:
(B) VIBGYOR

Question 106.
The entire range of electromagnetic wave frequencies is known as the ……………………… . ( )
(A) spectrum
(B) colour bands
(C) range of colours
(D) electromagnetic spectrum
Answer:
(D) electromagnetic spectrum

Question 107.
………………………. waves of electromagnetic spectrum are at shorter wavelengths. ()
(A) visible
(B) x – rays
(C) gamma rays
(D) U.V. rays
Answer:
(C) gamma rays

Question 108.
Planck’s equation …………………….. . ( )
(A) E=h
(B) Z=hk
(C) E=hυ
(D) h=Eυ
Answer:
(C) E=hυ

Question 109.
When an electron jumps from lower energy state to higher energy state spectrum emits. ( )
(A) emission
(B) absorption
(C) visible
(D) e.m.s.
Answer:
(B) absorption

Question 110.
Bohr model successfully explains the spectrum of …………………….. atom. ( )
(A) boron
(B) hydrogen
(C) beryllium
(D) All
Answer:
(B) hydrogen

Question 111.
The principal quantum number, which denotes the main shell ‘L.’ is …………………. . ( )
(A) 1
(B) 2
(C) 3
(D) 4
Answer:
(B) 2

Question 112.
The magnetic quantum number extends from …………………. to ………………………… for a given ‘I ‘ value. ( )
(A) -1 to + l
(B) l to (l-1)
(C) (l—1) to (l+1)
(D) l to (l-3)
Answer:
(A) -1 to + l

Question 113.
Maximum number of electrons that can be accommodated In d-subshell ……………….. . ()
(A) 8
(B) 10
(C) 12
(D) 14
Answer:
(B) 10

Question 114.
The anti-parallel spin of electron is represented by ( )
(A) -½
(B) 0
(C) -3
(D) +½
Answer:
(A) -½

Question 115.
The distribution of electrons in shells, sub-shells and orbitals in an atom is known as ………….. .
(A) atomic structure
(B) electronic configuration
(C) chemical formula
(D) accommodation of electrons
Answer:
(B) electronic configuration

Question 116.
The maximum number of electrons that can occupy a main shell (n) is …………….. .( )
(A) 2
(B) 2n²
(C) n²
(D) n
Answer:
(B) 2n²

Question 117.
The electronic configuration of ₁₃Al is ………………………. . ( )
(A) 1s² 2s² 2p⁶ 3s³
(B) 1s²2s² 2p⁶ 3s²
(C) 1s²2s²2p⁶3s²3p¹ (D) 1s²2s²2p⁶3s²3p⁶
Answer:
(C) 1s²2s²2p⁶3s²3p¹

Question 118.
………………………… is an intrinsic property of an electron. ( )
(A) emission of energy
(B) absorption of energy
(C) spin
(D) emission of radiation
Answer:
(C) spin

Question 119.
Electron in ………………………… orbit does not radiate energy. ( )
(A) s-orbital
(B) p-orbital
(C) stationary
(D) sub-stationary
Answer:
(D) sub-stationary

Question 120.
During formation of Rainbow, the water droplets act as ……………………. . ( )
(A) lense
(B) mirrors
(C) prisms
(D) carriers
Answer:
(C) prisms

Question 121.
Electromagnetic energy is characterized by …………………….. . ( )
(A) wavelength
(B) frequency
(C) A & B
(D) no character
Answer:
(C) A & B

Question 122.
………………… produce line spectrum. ( )
(A) consolidations
(B) liquid atoms
(C) gaseous atoms
(D) any atom
Answer:
(C) gaseous atoms

Question 123.
An atom or molecule having lowest possible energy is said to be in its …………… state. ( )
(A) ground
(B) excited
(C) melting
(D) freezing
Answer:
(A) ground

Question 124.
When an electron jumps from a lower energy state to higher energy state it energy. ( )
(A) loses
(B) emits
(C) absorbs
(D) no change
Answer:
(A) loses

Question 125.
Splitting of spectral lines In magnetic field is called ……………………….. effect. ( )
(A) stark
(B) streeking
(C) screening
(D) Zeeman
Answer:
(D) Zeeman

Question 126.
…………………………… quantum number gives spin of electrons about their own axes. ( )
(A) spin
(B) magnetic
(C) angular momentum
(D) principal
Answer:
(A) spin

Question 127.
If both spin quantum number values are positive then the spins are ………………… . ( )
(A) parallel
(B) perpendicular
(C) clock-wise
(D) antilock-wise
Answer:
(A) parallel

Question 128.
Atomic spectrum of hydrogen is a ……………………. spectrum. ( )
(A) line
(B) band
(C) Continuous
(D) visible
Answer:
(A) line

Question 129.
The shape of s-orbital is ……………………… . ( )
(A) dumbell
(B) double dumbell
(C) spherical
(D) no shape
Answer:
(C) spherical

Question 130.
The shape of p-orbital is ………………………… . ( )
(A) dumbell
(B) double dumbell
(C) spherical
(D) no shape
Answer:
(A) dumbell

Question 131.
The shape of d-orbital is …………………………. . ( )
(A) dumbell
(B) double dumbell
(C) spherical
(D) no shape
Answer:
(B) double dumbell

Question 132.
The electronic structure of the atom that is correctly explained by Bohr’s theory in the following is ………………………. . ( )
(A) Hydrogen atom
(B) Helium atom
(C) Carbon atom
(D) All atoms
Answer:
(A) Hydrogen atom