The maximum number of emission lines obtained when the excited electron of the H atom jumps from n = 6 to the ground state is -

The ionization energy for H atom in the ground state is 2.18 x 10^-18 J. The process energy requirements will be: (${}^{}{}^{}{}^{}+{}^{}$$\mathrm{}$

The ejection of the photoelectron from the silver metal can be stopped by applying a voltage of 0.35 eV when the radiation having a wavelength of 256.7 nm is used. The work function for silver metal is 

Property which is same for the following species is:

 N^3–, O^2–, F^–, Na⁺, Mg²⁺ and Al³⁺ 

The statement that is not correct for periodic classification of elements is 

Comprehension given below is followed by some multiple choice questions. Each question has one correct option. Choose the correct option.

In the modern periodic table, elements are arranged in order of configuration. Depending upon the type of orbitals receiving the last electron, the elements in the periodic table have been divided into four block, viz s, p, d and f.

The modern periodic table consists of 7 periods and 18 groups. Each period begins with the filling of a new energy shell. In accordance with the Aufbau principle, the seven periods (1 to 7) have 2, 8, 8, 18, 18, 32 and 32 elements respectively.

The seventh period is still incomplete. To avoid the periodic table being too long, the two series of f-block elements, called lanthanoids and actinoids are placed at the bottom of the periodic table

(i) The element with atomic number 57 belongs to 

The electronic configuration of the element which is just above the element with atomic number 43 in the same group is ______.

The total number of electrons present in one mole of methane is

$$\begin{gathered} 1. 6.023 \times {10}^{23} \\ 2. 6.023 \times {10}^{24} \\ 3. 6.023 \times {10}^{22} \\ 4. 1.619\times {10}^{23} \end{gathered}$$

The total number and mass of neutrons in 7 mg of ¹⁴C would be 

(Assume that mass of a neutron = 1.675 × 10^–27 kg)

$$\begin{gathered} 1. 2.41 \times {10}^{21} , 4.03 \times {10}^{–6} \mathrm{kg} \\ 2. 6.23 \times {10}^{23} , 1.67 \times {10}^{-21}\mathrm{kg} \\ 3. 1.22 \times {10}^{22} , 4.03 \times {10}^6 \mathrm{kg} \\ 4. 2.41 \times {10}^{21} , 4.03 \times {10}^{-6} \mathrm{g} \end{gathered}$$

The wave number of a light whose time period is 2.0 × 10^–10 s would be

The number of photons of light with a wavelength of 4000 pm that provide 1J of energy would be 

$$\begin{gathered} 1. 2.01 \times {10}^{16} \\ 2. 2.01 \times {10}^{19} \\ 3. 4.14 \times {10}^{23} \\ 4. 2.14 \times {10}^{21} \end{gathered}$$

Electromagnetic radiation of wavelength 242 nm is just sufficient to ionise sodium atom. The ionisation energy of sodium in kJ mol^-1 is -

A 25-watt bulb emits monochromatic yellow light with a wave length of 0.57µm. The rate of emission of quanta per second would be -

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 

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

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

The wave number for the longest wavelength transition in the Balmer series of atomic hydrogen would be -

$$\begin{gathered} 1. 1.52 \times {10}^6 {\mathrm{m}}^{-1} \\ 2. 3.14 \times {10}^6 {\mathrm{cm}}^{-1} \\ 3. 15.2 \times {10}^6 {\mathrm{m}}^{-1} \\ 4. 1.52 \times {10}^6 {\mathrm{cm}}^{-1} \end{gathered}$$

The energy of an electron in H - atom is given by E_n = $\frac{(–2.18 \times {10}^{-18} )}{{\mathrm{n}}^2}$ J.  The shortest wavelength of light that can be used to remove an electron completely from n = 2 orbit will be

$$\begin{gathered} 1. 3647 \stackrel{°}{\mathrm{A}} \\ 2. 5132 \stackrel{°}{\mathrm{A}} \\ 3. 3017 \stackrel{°}{\mathrm{A}} \\ 4. \mathrm{None} \mathrm{of} \mathrm{these} \end{gathered}$$

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

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:

$$\begin{gathered} 1. 1.33 \times {10}^7 \\ 2. 5.46 \times {10}^8 \\ 3. 1.33 \times {10}^9 \\ 4. 2.36 \times {10}^8 \end{gathered}$$

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

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

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

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 is 5.6 × 10²⁴, the power of the laser is:

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

If the photon detector receives a total of 3.15$\times {10}^{-18}$ J from the radiation of 600 nm, the number of photons received by the detector would be 

$$\begin{gathered} 1. {10}^2 \\ 2. 10 \\ 3. 50 \\ 4. 20 \end{gathered}$$

A radiation source emitted  2.5 × 10¹⁵ photons in 2 nanoseconds. Energy of the source is -

$$\begin{gathered} 1. 8.28 \times {10}^{-10} \mathrm{J} \\ 2. 8.24 \times {10}^{10} \mathrm{J} \\ 3. 7.12 \times {10}^{-11} \mathrm{J} \\ 4. 2.12 \times {10}^{ 10} \mathrm{J} \end{gathered}$$

Emission transitions in the Paschen series end at orbit n = 3 and start from orbit n and can be represented as v = 3.29 × 10¹⁵ (Hz)$\left(\frac{1}{3^2}- \frac{1}{{\mathrm{n}}^2}\right)$. The value of n if the transition is observed at 1285 nm is -$\mathrm{}$

If the velocity of the electron is 1.6 × 10⁶ ${\mathrm{ms}}^{-1}$. The de Broglie wavelength associated with this electron is 

$$\begin{gathered} 1. 590 \mathrm{pm} \\ 2. 455 \mathrm{pm} \\ 3. 512 \mathrm{pm} \\ 4. 401 \mathrm{pm} \end{gathered}$$

If the wavelength of a neutron is 800 pm, then the characteristic velocity associated with the neutron is