Which of the following series of transitions in the spectrum of hydrogen atoms falls in the visible region?

1. Brackett series

2. Lyman series

3. Balmer series

4. Paschen series

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 nm 

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

The wavelength of light emitted when the electron in a H atom undergoes the transition from an energy level with n = 4 to an energy level with n = 2, is :

1. 586 mm

2. 486 nm

3. 523 nm

4. 416 pm

The energy and the radius of the first orbit of He⁺ are respectively :

1. \(-8.72\times 10^{-18}J\); 0.02645 nm

2. \(8.72\times 10^{-18}J\); 0.02645 nm

3. \(-7.82\times 10^{-18}J\) ; 0.03655 nm

4. \(7.82\times 10^{-18}J\); 0.03655 nm

Determine the maximum number of emission lines produced when an electron in a hydrogen atom transitions from the n = 6  energy level to the ground state :

1. 30

2. 21

3. 15

4. 28

The energy associated with the fifth orbit of a hydrogen atom is :

$1.$ $-2.18$ $\times$ ${10}^{-18}$ $\mathrm{J}$
$2.$ $-8.72$ $\times$ ${10}^{-20}$ $\mathrm{J}$
$3.$ $-3.88$ $\times$ ${10}^{-21}$ $\mathrm{J}$
$4.$ $-8.72$ $\times$ ${10}^{-19}$ $\mathrm{J}$