The work function of a photoelectric material is 3.3 eV. Its threshold frequency will be:
(A) 4 × 10²³ Hz
(B) 8 × 10¹² Hz
(C) 4 × 10¹¹ Hz
(D) 8 × 10¹⁴ Hz

To find the threshold frequency for a photoelectric material given its work function, you can use the photoelectric equation:

\[ E = h f \]

where:
- \( E \) is the work function of the material,
- \( h \) is Planck's constant,
- \( f \) is the threshold frequency.

Given:
- Work function (\( E \)) = 3.3 eV
- Planck's constant (\( h \)) = \( 6.626 \times 10^{-34} \) Js (joule-seconds)

First, convert the work function from electron volts (eV) to joules (J). The conversion factor is:

\[ 1 \text{ eV} = 1.602 \times 10^{-19} \text{ J} \]

Thus:

\[ 3.3 \text{ eV} = 3.3 \times 1.602 \times 10^{-19} \text{ J} \]
\[ E = 5.288 \times 10^{-19} \text{ J} \]

Now, use the photoelectric equation to solve for \( f \):

\[ f = \frac{E}{h} \]
\[ f = \frac{5.288 \times 10^{-19} \text{ J}}{6.626 \times 10^{-34} \text{ Js}} \]
\[ f \approx 8 \times 10^{14} \text{ Hz} \]

So, the threshold frequency is:

**D) \( 8 \times 10^{14} \) Hz**