A particular station of All India Radio, New Delhi, broadcasts on a frequency of 1,368 kHz (kilohertz). The wavelength of the electromagnetic radiation emitted by the transmitter is : [speed of light, $\mathrm{c}=3.0\times {10}^8$ ${\mathrm{ms}}^{-1}$]

1.	2192 m	2.	21.92 cm
3.	219.3 m	4.	219.2 m

When electromagnetic radiation of wavelength 300 nm falls on the surface of sodium, electrons are emitted with a kinetic energy of 1.68 ×10⁵ J mol^–1. The minimum energy needed to remove an electron from sodium and the maximum wavelength that will cause a photoelectron to be emitted are respectively-

1. 2.31 × 10⁵ J mol^–1, 517 nm

2. 23.1 × 10⁵ J mol^–1, 517 nm

3. 3.31 × 10⁵ J mol^–1, 417 nm

4. 33.1 × 10⁵ J mol^–1, 417 nm

The frequency and wavelength of a photon emitted during a transition from n = 5 state to the n = 2 state in the hydrogen atom  are respectively-

1.  \(6.91\times10 ^{14} Hz\);   543 nm

2. \(7.91\times10 ^{14} Hz\); 434 nm

3. \(6.91\times10 ^{14} Hz\); 434

4. \(7.91\times10 ^{14} Hz\); 343 nm

Kinetic Energy of an electron is 3.0×10^–25 J. The wavelength of the electron will be-

1. 886.7 nm

2. 896.7 nm

3. 990.7 nm

4. 880.7 nm

The graph that represents the variation of  ${\mathrm{\psi }}^2$ (probability of density of finding the electron) with distance (r) is given below:

The number of nodes as per the graph is-

1. zero

2. 1

3. 2

4. Cannot predict

The ultraviolet region in the above figure is indicated by -

1. D

2. B

3. A

4. C

The neon gas emits radiation of 616 nm. The number of quanta that are present in 2 J of energy is:

$1.$ $6.2$ $\times$ ${10}^{-18}$
$2.$ $5.6$ $\times$ ${10}^{17}$
$3.$ $6.2$ $\times$ ${10}^{18}$
$4.$ $32.2$ $\times$ ${10}^{-20}$
$$

Which among the following are isoelectronic species?

1. ${\mathrm{Na}}^{+}, {\mathrm{K}}^{+}, {\mathrm{Ca}}^{2+}, {\mathrm{Mg}}^{2+}$

2. ${\mathrm{Ca}}^{2+}, {\mathrm{Mg}}^{2+}, {\mathrm{S}}^{2-}, {\mathrm{K}}^{+}$

3. ${\mathrm{Ca}}^{2+}, \mathrm{Ar}, {\mathrm{S}}^{2-}, {\mathrm{K}}^{+}$

4. None of the above

The circumference of the Bohr orbit for the H atom is related to the de Broglie wavelength associated with the electron revolving around the orbit by the following relation: 

$1.$ $2\mathrm{\pi r}=\mathrm{n\lambda }$

$2.$ $\mathrm{\pi r}$ $=$ $2\mathrm{n\lambda }$

$3.$ $\mathrm{mvr}$ $=$ $\mathrm{n\lambda }$

$4.$ $\mathrm{vr}$ $=$ $2\mathrm{n\lambda }$

The atomic number of elements whose outermost electronic configuration are represented by 3s¹ and 2p⁵ respectively, is: