NEET Structure of Atom — Set 16

Question 1

An electron in $ \text{Be}^{3+} $ has an angular momentum of $ 6.33 \times 10^{-34} \, \text{J s} $. What is its energy? ($ h = 6.626 \times 10^{-34} \, \text{J s} $, $ E_1 $ for H = $ -2.18 \times 10^{-18} \, \text{J} $)

Accepted Answer

$ n = \frac{L \cdot 2\pi}{h} = \frac{6.33 \times 10^{-34} \times 2 \times 3.14}{6.626 \times 10^{-34}} = 6 $. For $ \text{Be}^{3+} $ (Z = 4), $ E_6 = -16 \times 2.18 \times 10^{-18} / 36 = -9.6778 \times 10^{-19} \, \text{J} $.

Question 2

The angular momentum of an electron in the fourth orbit of $ \text{He}^+ $ is $ 4.22 \times 10^{-34} \, \text{J s} $. What is the frequency of the photon emitted when it falls to the second orbit? ($ h = 6.626 \times 10^{-34} \, \text{J s} $, $ E_1 $ for H = $ -2.18 \times 10^{-18} \, \text{J} $)

Accepted Answer

$ n = \frac{L \cdot 2\pi}{h} = \frac{4.22 \times 10^{-34} \times 2 \times 3.14}{6.626 \times 10^{-34}} = 4 $. For $ \text{He}^+ $ (Z = 2), $ E_2 = -4 \times 2.18 \times 10^{-18} / 4 = -2.18 \times 10^{-18} \, \text{J} $, $ E_4 = -4 \times 2.18 \times 10^{-18} / 16 = -5.45 \times 10^{-19} \, \text{J} $. $ \Delta E = 1.635 \times 10^{-18} \, \text{J} $. $ v = \frac{\Delta E}{h} = 2.467 \times 10^{15} \, \text{Hz} $.

Question 3

Which quantum number determines the shape of an orbital?

Accepted Answer

The azimuthal quantum number $ l $ determines the shape of an orbital (e.g., s, p, d).

NEET Chemistry: Structure of Atom — Practice Set 16

Q1. An electron in \( \text{Be}^{3+} \) has an angular momentum of \( 6.33 \times 10^{-34} \, \text{J s} \). What is its energy? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( E_1 \) for H = \( -2.18 \times 10^{-18} \, \text{J} \))

Q3. Which quantum number determines the shape of an orbital?

Q4. An atom has 26 protons, 30 neutrons, and 24 electrons. What is its mass number and charge?

Q5. The energy of an electron in the second orbit of \( \text{He}^+ \) is \( -13.6 \, \text{eV} \). What is the ionization energy from the fourth orbit? (\( 1 \, \text{eV} = 1.6 \times 10^{-19} \, \text{J} \))

Q6. How many orbitals in an atom can have the quantum numbers \( n = 4 \) and \( l = 3 \)?

Q7. An atom has 32 protons, 38 neutrons, and 30 electrons. What is its mass number and charge?

Q8. Which transition in a hydrogen atom corresponds to the emission in the ultraviolet region?

Q9. The velocity of an electron in the first orbit of a hydrogen atom is \( 2.19 \times 10^6 \, \text{m s}^{-1} \). What is its velocity in the third orbit?

Q10. An atom has 20 protons, 22 neutrons, and 18 electrons. What is its mass number and charge?