If the speed of electron in Bohr's first orbit of hydrogen atom be x, then speed of the electron in 3rd orbit is:

1. x/9

2. x/3

3. 3x

4. 9x

In Bohr's model of the hydrogen atom the ratio between the period of revolution of an electron in the orbit n=1 to the period of revolution of the electron in the orbit n=2 is

1. 1:2

2. 2:1

3. 1:4

4. 1:8

A cricket ball of 0.5 kg is moving with a velocity of 100 ms^-1. The wavelength associated with its motion is:

1. 1/100cm

2. 6.6 x 10^-34m

3. 1.32 x 10^-35m

4. 6.6 x 10^-28m

If uncertainties in the measurement of position and momentum are equal, what is the uncertainty in the measurement of velocity?

1. $\frac{1}{2}\sqrt{\frac{mh}{\mathrm{\pi }}}$ 

2. $\frac{1}{2\mathrm{\pi }}\sqrt{\frac{h}{m}}$

3.$\frac{1}{2m}\sqrt{\frac{h}{\mathrm{\pi }}}$

4. None of the above.

What is the number of electrons in ₁₉ K with quantum numbers n=3 and l=0?

1. Two (2)

2. One (1)

3. Four (4)

4. Three (3)

The ratio of the difference in energy between the first and second Bohr orbit of H to that between the second and the third Bohr orbit is 

1. 1/2

2. 1/3

3. 4/9

4. 27/5

The number of orbitals that are possible at the L-energy level is

1. 2

2. 4

3. 6

4. 1

The radius of second stationary orbit in Bohr's atom is R. The radius of 3^rd orbit will be:-

1. 9R

2. R/4

3. 9R/4

4. 2R

Which of the following is not correctly matched?

1. Energy associated with Bohr's orbit  \(E =\dfrac{-2.18 \times 10^{-18} \times Z^{2}}{n^{2}}\)

2. Energy gap between two orbits \(\Delta E=-h c Z^{2} R_{H}\left[\frac{1}{n_{1}{ }^{2}}-\frac{1}{n^{2}{ }_{2}}\right]\)

3. Kinectic energy of the ejected electron \(hv = hv_0 + \dfrac{1}{2}mv^2\)

4. Energy of one mole of photons \(E = N_0hv/C\)

If the velocity of a particle is reduced to 1/3^rd, then percentage increase in its de-broglie wavelength will be:-

1. 100%

2. 200%

3. 50%

4. 33.33%