The table below shows the threshold frequency of radiation for photoelectric emission for some metals - Scottish Highers Physics - Question 11 - 2016

To determine which metals can emit photoelectrons when irradiated with a frequency of 6 × 10^14 Hz, we must compare this frequency to the threshold frequencies of each metal provided in the table.

1. Sodium: The threshold frequency is 4 × 10^14 Hz. Since 6 × 10^14 Hz > 4 × 10^14 Hz, sodium can emit photoelectrons.

2. Potassium: The threshold frequency is 5 × 10^14 Hz. Since 6 × 10^14 Hz > 5 × 10^14 Hz, potassium can also emit photoelectrons.

3. Zinc: The threshold frequency is 6 × 10^14 Hz. Since 6 × 10^14 Hz = 6 × 10^14 Hz, zinc is at its threshold and can just emit photoelectrons but only minimally.

From the analysis, sodium and potassium both can emit photoelectrons when irradiated with the given frequency, making the correct answer:

D. sodium and potassium only.