(i) State two important features of Einstein's photoelectric equation.
(ii) Radiation of frequency `10^(15)Hz` is incident on two photosenstive surface P and Q. There is no photoemission from surface P. Photoemission occurs from Q but photoelectrons have zero kinetic energy. Explain these observation and find the value of work function for surface Q.

Explanation

### Step-by-Step Solution:

#### (i) Two Important Features of Einstein's Photoelectric Equation

1. **Threshold Frequency Condition**:
The first important feature of Einstein's photoelectric equation is that for photoemission to occur, the frequency of the incident radiation (ν) must be greater than or equal to the threshold frequency (ν₀) of the material. This means:
\[
ν \geq ν₀
...