The number of N atoms in 681 g of C₇H₅N₃O₆ is x $\times$ 10²¹. The value of x is (N_A = 6.02 $\times$ 10²³ mol^$-$1) (Nearest Integer)

When the excited electron of a H atom from n = 5 drops to the ground state, the maximum number of emission lines observed are _____________.

Consider the following set of quantum numbers.

The de-Broglie's wavelength of an electron in the $4^{\text {th }}$ orbit is ________ $\pi \mathrm{a}_0$. ( Bohr's radius)

If wavelength of the first line of the Paschen series of hydrogen atom is 720 nm, then the wavelength of the second line of this series is _________ nm. (Nearest integer)

The number of atomic orbitals from the following having 5 radial nodes is ___________.

$7 \mathrm{s}, 7 \mathrm{p}, 6 \mathrm{s}, 8 \mathrm{p}, 8 \mathrm{d}$

Based on Heisenberg's uncertainty principle, the uncertainty in the velocity of the electron to be found within an atomic nucleus of diameter $10^{-15} \mathrm{~m}$ is ________ $\times 10^9 \mathrm{~ms}^{-1}$ (nearest integer)

Frequency of the de-Broglie wave of electron in Bohr's first orbit of hydrogen atom is _________ $\times 10^{13} \mathrm{~Hz}$ (nearest integer).

[Given : $\mathrm{R}_{\mathrm{H}}$ (Rydberg constant) (Plank's constant) .]

For hydrogen atom, energy of an electron in first excited state is $-3.4 \mathrm{~eV}, \mathrm{K} . \mathrm{E}$. of the same electron of hydrogen atom is $x \mathrm{~eV}$. Value of is _________ . (Nearest integer)

If the uncertainty in velocity and position of a minute particle in space are, 2.4 $\times$ 10^$-$26 (m s^$-$1) and 10^$-$7 (m) respectively. The mass of the particle in g is ____________. (Nearest integer)

Electrons in a cathode ray tube have been emitted with a velocity of 1000 m s$^{-1}$. The number of following statements which is/are $\underline {\mathrm{true}}$ about the emitted radiation is ____________.

In the given reaction,

$X+Y+3 Z \leftrightarrows X YZ_{3}$

If the $x$-intercept of a focal chord of the parabola $y^{2}=8x+4y+4$ is 3, then the length of this chord is equal to ____________.

The longest wavelength of light that can be used for the ionisation of lithium atom (Li) in its ground state is x $\times$ 10^$-$8 m. The value of x is ___________. (Nearest Integer).

(Given : Energy of the electron in the first shell of the hydrogen atom is $-$2.2 10 ms)

The minimum uncertainty in the speed of an electron in an one dimensional region of length $2 \mathrm{a}_{\mathrm{o}}$ (Where $\mathrm{a}_{\mathrm{o}}=$ Bohr radius ) is _________ .

116 g of a substance upon dissociation reaction, yields 7.5 g of hydrogen, 60 g of oxygen and 48.5 g of carbon. Given that the atomic masses of H, O and C are 1, 16 and 12, respectively. The data agrees with how many formulae of the following?

A. CH₃COOH, B. HCHO, C. CH₃OOCH₃, D. CH₃CHO

The number of following statement/s which is/are incorrect is ___________

(A) Line emission spectra are used to study the electronic structure

(B) The emission spectra of atoms in the gas phase show a continuous spread of wavelength from red to violet

(C) An absorption spectrum is like the photographic negative of an emission spectrum

(D) The element helium was discovered in the sun by spectroscopic method