The product formed is an isobar , if there is :

• 1 $\mathrm{\alpha }$ emission

• 1 $\mathrm{\beta }$ emission

• 1 $\mathrm{\alpha }$ and 1 $\mathrm{\beta }$ emission

• 2 $\mathrm{\alpha }$ and 2 $\mathrm{\beta }$ emission

When ${}_{13}{}^{27}\mathrm{Al}$ is bombarded with $\mathrm{\alpha }$ - particle , a radioactive isotope of phosphorus ${}_{15}{}^{30}\mathrm{P}$ is formed .Which particle is emitted along with ${}_{15}{}^{30}\mathrm{P}$ ?

• Deuteron

• Proton

• Electron

• Neutron

Smallest wavelength occurs for

• Lyman series

• Balmer series

• Paschen series

• Brackett series

Which of the following is wrong for Bohr model?

• It establishes stability of atom

• It is inconsistent with Heisenberg uncertainty principle.

• It explains the concept of spectral lines for hydrogen like species.

• Electrons behave as particle and wave

625.

Assume that you are travelling at a speed of 90 km/h in a small car with a mass of 1050 kg. If the uncertainty in the velocity of the car is 1% ($∆$ = 0.9 km/h), what is the uncertainty (in meters) in the position of the car ?

• $∆\mathrm{x} \ge 1\times {10}^{-35}\mathrm{m}$

• $∆\mathrm{x} \ge 2 \times {10}^{-37}\mathrm{m}$

• $∆\mathrm{x} \ge 2\times {10}^{-36} \mathrm{m}$

• $∆\mathrm{x} \ge 4 \times {10}^{-38}\mathrm{m}$

For a certain particle , it is found that uncertainty in velocity is reciprocal of uncertainty in position .This implies that :

• mass of particle > unity

• mass of particle = unity

• mass of particle $\le$ h

• mass of particle $\ge$ h / 4$\mathrm{\pi }$

Which of the following sets of quantum numbers is not possible ?

• n = 4 , l =1 , m = 0 , s = $+ \frac{1}{2}$

• n = 4 , l = 3 , m = - 3 , s = $- \frac{1}{2}$

• n = 4 , l = 1 , m = + 2 , s = $- \frac{1}{2}$

• n = 4 , l = 0 , m = 0 , s = $- \frac{1}{2}$

What is the frequency of a X-ray photon whose momentum is 1.1 x 10^-23 kg-ms^-2 ?

• 5 x 10¹⁶ Hz

• 0.5 x 10²⁷ Hz

• 0.5 x 10¹⁸ Hz

• 5 x 10¹⁸ Hz

The magnitude of orbital angular momentum of an electron of azimuthal quantum number 2 is :

• $\frac{2\mathrm{h}}{2\mathrm{\pi }}$

• $\frac{\sqrt{6}\mathrm{h}}{2\mathrm{\pi }}$

• $\frac{\sqrt{2}\mathrm{h}}{2\mathrm{\pi }}$

• $\frac{6\mathrm{h}}{2\mathrm{\pi }}$

For an electron , if the uncertainty in velocity is $∆$v , the uncertainty in its position ($∆$x)  is given by :

• $\frac{\mathrm{hm}}{4\mathrm{\pi }∆\mathrm{\nu }}$

• $\frac{4\mathrm{\pi }}{\mathrm{hm}∆\mathrm{\nu }}$

• $\frac{\mathrm{h}}{4\mathrm{\pi m}∆\mathrm{v}}$

• $\frac{4\mathrm{\pi m}}{\mathrm{h}∆\mathrm{\nu }}$