Question 1

Which experimental observation provided direct evidence for the wavelike properties of electrons, as predicted by de Broglie?

Accepted Answer

The diffraction patterns of electrons passing through a crystal

Question 2

According to de Broglie, the wavelength $$\lambda of a $$particle is given by which equation?

Accepted Answer

$$\lambda = \dfrac{h}{p}$$

Question 3

A baseball (mass = $$0.145 kg) is $$thrown at $$40 m/s. $$Calculate its de Broglie wavelength. ($$h = 6.626 	imes 10$$^{-34}$$ J·s)

Accepted Answer

$$1.14 	imes 10$$^{-34}$$ m

Question 4

Which statement best describes the Heisenberg Uncertainty Principle?

Accepted Answer

It is impossible to measure both the exact position and momentum of a particle at the same time.

Question 5

What does the square of the wavefunction, $$\$$psi^2$$, represent in quantum mechanics?

Accepted Answer

The probability density of finding an electron at a given point in space

Question 6

Which of the following sets of quantum numbers is NOT allowed for an electron in an atom?

Accepted Answer

$$n = 2, \ell = 3, m_\ell = -3$$

Question 7

The energy of an electron in a hydrogen atom depends on which quantum number?

Accepted Answer

The principal quantum number $$n$$

Question 8

Which orbital designation is correct for an electron with $$n = 3$$, $$\ell = 2$$, $$m_\ell = 0$$?

Accepted Answer

3d

Question 9

How many angular nodes are present in a 3p orbital?

Accepted Answer

1

Question 10

Which of the following best describes the shape of a 2p orbital?

Accepted Answer

Dumbbell-shaped

Question 11

Which quantum number determines the orientation of an orbital in space?

Accepted Answer

Magnetic quantum number $$m_\ell$$

Question 12

What is the total number of orbitals in the $$n = 2$$ shell?

Accepted Answer

4

Question 13

Which of the following statements about s orbitals is TRUE?

Accepted Answer

They are spherical in shape.

Question 14

How many radial nodes are present in a 3s orbital?

Accepted Answer

2

Question 15

Which of the following best explains why the diffraction pattern for electrons is similar to that for X-rays?

Accepted Answer

Both electrons and X-rays exhibit wave-like behavior.

Question 16

Which quantum number(s) must have integer values?

Accepted Answer

All of $$n$$, $$\ell$$, and $$m_\ell$$

Question 17

The Schrödinger equation for the hydrogen atom can be separated into which two parts?

Accepted Answer

Radial and angular parts

Question 18

Which of the following is a correct statement about the probability density of an electron in a hydrogen 1s orbital?

Accepted Answer

It is highest at the nucleus and decreases with distance.

Question 19

Which of the following orbitals has both radial and angular nodes?

Accepted Answer

3d

Question 20

If an electron is described by the quantum numbers $$n = 4$$, $$\ell = 2$$, $$m_\ell = 0$$, what is the orbital designation?

Accepted Answer

4d

Lec 4 notes chem

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