The work function $(\phi)$ of some metals is listed below. The number of metals which will show photoelectric effect when light of $300 \ nm$ wavelength falls on the metal is

Metal	$Li, Na, K, Mg, Cu, Ag, Fe, Pt, W$
$\phi \ (eV)$	$2.4, 2.3, 2.2, 3.7, 4.8, 4.3, 4.7, 6.3, 4.75$

The ratio of the energy of a photon with wavelength $3000 \ \mathring{A}$ to that of a photon with wavelength $6000 \ \mathring{A}$ is:

Given below are two statements about $X$-ray spectra of elements :
Statement $(I) :$ $A$ plot of $\sqrt{\nu}$ ($\nu =$ frequency of $X$-rays emitted) vs atomic mass is a straight line.
Statement $(II) :$ $A$ plot of $\nu$ ($\nu =$ frequency of $X$-rays emitted) vs atomic number is a straight line.
In the light of the above statements choose the correct answer from the options given below :

$a$,$b$,$c$,$d$ are electromagnetic radiations. Frequencies of $a$,$b$ are $3 \times 10^{15} \ Hz$,$2 \times 10^{14} \ Hz$,respectively,whereas wavelengths of $c$,$d$ are $400 \ nm$,$750 \ nm$,respectively. The increasing order of their energies is

With regard to the photoelectric effect,identify the correct statement among the following.

The following sketch represents a specific wave of light. What will be the color of the light represented by this wave?