Emission and Absorption Spectra

Q. Velocity of electron in $2^{nd}$ orbit of $H{e}^{+}$ is

1. $2.18\times {10}^{3}m/s$
2. $2.18\times {10}^{6}m/s$
3. $4.36\times {10}^{6}m/s$
4. $4.36\times {10}^{3}m/s$

Q. In Bohr series of lines of hydrogen spectrum, the emission of a line from the red end corresponds to which one of the following inner-orbit jump of the electron in a hydrogen atom?

1. 
2. 
3. 
4. 

Q.

When an electron jumps from L to K shell

1. Energy is absorbed

2. Energy is released

3. Energy is sometimes absorbed and sometimes released

4. Energy is neither absorbed nor released

Q.

Match the following:

$\begin{array}{cc}\text{a) Lyman (r, t)}& \text{p) visible}\\ \text{b) Balmer (p)}& \text{q) Infrared}\\ \text{c) Paschen (q, s)}& \text{r) Ultraviolet}\\ \text{d) Brackett (q)}& \text{s)}{n}_2=4,n_1=3\\ & \text{t)}{n}_2=5,n_1=1\end{array}$

1. a > r; b > q; c > p, s; d > s

2. a > t; b > p; c > q; d > q

3. a > p, t; b > q; c > s; d > q

4. a > r, t; b > p; c > q, s; d > q

Q.

A hydrogen atom in its ground state is irradiated by light of wavelength 970Å. Taking hc/e = 1.237 x ${10}^{-6}$eV m and the ground state energy of hydrogen atom as - 13.6 eV, the number number of lines present in the emission spectrum is:___

Q.

Given the value of Rydberg Constant is ${10}^{-7}{m}^{-1}$, the wave number of last line of the Balmer series in hydrogen spectrum will be:

1. $0.025\times {10}^4{m}^{-1}$

2. $0.25\times {10}^{-7}{m}^{-1}$

3. $2.5\times {10}^{-7}{m}^{-1}$

4. $2.5\times {10}^7{m}^{-1}$

Q. Which of the following electron transition in a hydrogen atom will require the largest amount of energy input?

1. from n = 1 to n = 2
2. from n = 3 to n = 5
3. from n = 5 to n = 1
4. from n = 2 to n = 4

Q. How many spectral lines are produced, when an electron jumps from n = 5 to ground state (n=1)?

1. 5
2. 10
3. 26
4. 14

Q.

The spectrum of He is expected to be similar to

1. H

2. Li⁺

3. Na

4. He⁺

Q. Which one of the following statements is incorrect?

1. Rydberg’s constant and wave number have same units.
2. Lyman series of hydrogen spectrum occurs in u.v region
3. Angular momentum of an electron in the ground state of hydrogen atom =
4. The radius of first orbit of hydrogen atom is