The energy of an electron in an H - atom is given by \(E_n=(-2.18 \times10^{-18})/n^2~\mathrm J.\) The shortest wavelength of light that can be used to remove an electron completely from \(n = 2\) orbit will be:

1.	\(3647~\mathring{\mathrm A}\)	2.	\(5132~\mathring{\mathrm A}\)
3.	\(3017~\mathring{\mathrm A}\)	4.	None of these

The wavelength of an electron moving with a velocity of 2.05 × 10⁷ m s^–1  would be:  

\(1 .\) \(4 . 65\) \(\times\) \(10^{- 12}\) \(m\)

\(2 .\) \(3 . 55\) \(\times\) \(10^{-11}\) \(m\)

\(3 .\) \(2 . 34\) \(\times\) \(10^{11}\) \(m\)

\(4 .\) \(6 . 43\) \(\times\) \(10^{ -11}\) \(m\)

The lowest value of n for 'g' orbitals is :

An atom of an element contains 29 electrons and 35 neutrons. The number of protons in the element would be:

If the diameter of a carbon atom is 0.15 nm, the number of carbon atoms that can be placed side by side in a straight line across the length of the scale of length 20 cm long will be:$\mathrm{}$

The charge on the oil drop is –1.282 × 10^–18C. The number of electrons present in it would be :

1. 15

2. 8

3. 2

4. 6

An element with a mass number of 81 contains 31.7% more neutrons as compared to protons. The atomic symbol of the element would be :

$1.$ ${}_{35}{}^{81}\mathrm{Br}$
$2.$ ${}_{36}{}^{81}\mathrm{Br}$
$3.$ ${}_{35}{}^{79}\mathrm{Br}$
$4.$ ${}_{36}{}^{79}\mathrm{Br}$

An ion with mass number 37 possesses one unit of negative charge,the ion contains 11.1% more neutrons than the electrons. The symbol of the ion is-

$$\begin{gathered} 1. {}_{18}{}^{37}\mathrm{Cl} \\ 2. {}_{17}{}^{37}\mathrm{Cl} \\ 3. {}_{19}{}^{38}\mathrm{Cl} \\ 4. {}_{19}{}^{37}\mathrm{Cl} \end{gathered}$$

A nitrogen laser produces radiation at a wavelength of 337.1 nm. If the number of photons emitted per second is 5.6 × 10²⁴,
the power of the laser is:

$\mathrm{}$$1.$ $4.56$ $\times$ ${10}^7$ $\mathrm{J}$
$2.$ $3.33$ $\times$ ${10}^6$ $\mathrm{J}$
$3.$ $1.29$ $\times$ ${10}^6$ $\mathrm{J}$
$4.$ $9.17$ $\times$ ${10}^5$ $\mathrm{J}$

A photon detector receives a total energy of \(3.15 \times 10^{-18}\) J from radiation with a wavelength of 600 nm. How many photons are received by the detector?

$1.$ ${10}^2$
$2.$ $10$
$3.$ $50$
$4.$ $20$