If $a$0 is denoted as the Bohr radius of hydrogen atom, then what is the de-Broglie wavelength (λ) of the electron present in the second orbit of hydrogen atom? [n : any integer]

Radius of the first excited state of Helium ion is given as : ${\mathrm{a}}_0\to$ radius of first stationary state of hydrogen atom.

Which of the following is/are not correct with respect to energy of atomic orbitals of hydrogen atom?(A) 1s < 2p < 3d < 4s(B) 1s < 2s = 2p < 3s = 3p(C) 1s < 2s < 2p < 3s < 3p(D) 1s < 2s < 4s < 3dChoose the correct answer from the options given below :

Given below are two statements : Statement (I) : A spectral line will be observed for a $2p_x\to 2p_y$ transition. Statement (II) : $2{\mathrm{p}}_x$ and $2{\mathrm{p}}_y$ are degenerate orbitals. In the light of the above statements, choose the correct answer from the options given below :

Heat treatment of muscular pain involves radiation of wavelength of about 900 nm . Which spectral line of H atom is suitable for this? Given : Rydberg constant ${\mathrm{R}}_{\mathrm{H}}=10^5{\mathrm{cm}}^{-1},\mathrm{h}=6.6\times 10^{-34}\mathrm{J}\mathrm{s},\mathrm{c}=3\times 10^8\mathrm{m}/\mathrm{s})$

Given below are two statements : Statement (I) : For a given shell, the total number of allowed orbitals is given by $n^2$. Statement (II) : For any subshell, the spatial orientation of the orbitals is given by $-l$ to $+l$ values including zero. In the light of the above statements, choose the correct answer from the options given below :

Given below are two statements about X-ray spectra of elements : Statement (I) : A plot of $\sqrt{v}$ ( $v=$ frequency of X-rays emitted) vs atomic mass is a straight line. Statement (II) : A plot of $v(\nu =$ frequency of $X$-rays emitted) vs atomic number is a straight line. In the light of the above statements, choose the correct answer from the options given below :

For hydrogen atom, the orbital/s with lowest energy is/are : (A) $4s$ (B) $3{\mathrm{p}}_x$ (C) $3{\mathrm{d}}_{x^2-y^2}$ (D) $3{\mathrm{d}}_{z^2}$ (E) $4{\mathrm{p}}_z$ Choose the correct answer from the options given below :

In a multielectron atom, which of the following orbitals described by three quantum numbers will have same energy in absence of electric and magnetic fields? A. $\mathrm{n}=1,\mathrm{l}=0,{\mathrm{m}}_1=0$ B. $\mathrm{n}=2,\mathrm{l}=0,{\mathrm{m}}_1=0$ C. $\mathrm{n}=2,\mathrm{I}=1,{\mathrm{m}}_1=1$ D. $\mathrm{n}=3,\mathrm{l}=2,{\mathrm{m}}_1=1$ E. $\mathrm{n}=3,\mathrm{l}=2,{\mathrm{m}}_1=0$ Choose the correct answer from the options given below:

Correct statements for an element with atomic number 9 are:A. There can be 5 electrons for which $m_s=+\frac{1}{2}$ and 4 electrons for which $m_s=-\frac{1}{2}$.B. There is only one electron in $p_z$ orbital.C. The last electron goes to orbital with $n = 2$ and $l = 1$.D. The sum of angular nodes of all the atomic orbitals is 1.Choose the correct answer from the options given below:

According to Bohr's model of hydrogen atom, which of the following statement is incorrect?

Which of the following statements are correct, if the threshold frequency of caesium is $5.16\times$ $10^{14}\mathrm{Hz}$ ? A. When Cs is placed inside a vacuum chamber with an ammeter connected to it and yellow light is focused on Cs , the ammeter shows the presence of current. B. When the brightness of the yellow light is dimmed, the value of the current in the ammeter is reduced. C. When a red light is used instead of the yellow light, the current produced is higher with respect to the yellow light. D. When a blue light is used, the ammeter shows the formation of current. E. When a white light is used. the ammeter shows formation of current. Choose the correct answer from the options given below:

Which of the following statements are true? (A) The subsidiary quantum number $l$ describes the shape of the orbital occupied by the electron. (B) is the boundary surface diagram of the $2{\mathrm{p}}_x$ orbital. (C) The + and - signs in the wave function of the $2p_x$ orbital refer to charge. (D) The wave function of $2{\mathrm{p}}_x$ orbital is zero everywhere in the $x y$ plane. Choose the correct answer from the options given below :

Which of the following postulate of Bohr's model of hydrogen atom is not in agreement with quantum mechanical model of an atom?

Consider the ground state of chromium atom $(Z=24)$. How many electrons are with Azimuthal quantum number $l=1$ and $l=2$ respectively ?

The extra stability of half-filled subshell is due to : (A) Symmetrical distribution of electrons (B) Smaller coulombic repulsion energy (C) The presence of electrons with the same spin in non-degenerate orbitals (D) Larger exchange energy (E) Relatively smaller shielding of electrons by one another Indentify the correct statements :

Which one of the following about an electron occupying the 1 s orbital in a hydrogen atom is incorrect? (Bohr's radius is represented by ${\mathrm{a}}_0$)

For electrons in ' 2 s ' and ' 2 p ' orbitals, the orbital angular momentum values, respectively are :

The type of oxide formed by the element among Li, Na, Be, Mg, B and Al that has the least atomic radius is :

First ionisation enthalpy values of first four group 15 elements are given below. Choose the correct value for the element that is a main component of apatite family :