NEET Questions Solved

Which type of radiation is not emitted by the electronic structure of atoms:

(A) Ultraviolet light

(B) X-rays

(C) Visible light

(D) y-rays

Velocity of helium atom at 300 K is 2.40 x 10² meter per sec. What is its wavelength? (mass number of helium is 4) -

(A) 0.416 nm

(B) 0.83 nm

(C) 803 Å

(D) 8000 Å

The frequency of line spectrum of sodium is 5.09 x 10¹⁴ sec^-1. Its wavelength (in nm) will be -[C= 3x10⁸m/sec]

(A) 510nm

(B) 420nm

(C) 589nm

(D) 622nm

When accelerated electrons are direct against an anticathode in an X-ray tube, the radiation obtained has a continuous spectrum with a wavelength minimum,

$\lambda$_min = (1.24 x 10^-6/V) m, where V is the voltage used for accelerating the electrons. Calculate $\lambda$_min for V= 5 x 10⁴ volts.

(A) 1.25 Å

(B) 0.75 Å

(C)0.25 Å

(D) 1.00 Å

The wavelengths of two photons are 2000 Å and 4000 Å respectively. What is the ratio of their energies?

(A) 1/4

(B) 4

(C) 1/2

(D) 2

Sodium atoms can be ionised by supplying an energy of 118 kcal mol^-1. Using this data, calculate the lowest possible frequency of light that can ionise a sodium atom.

(h = 6.624 x 10^-27 erg.sec, c= 3 x 10¹⁰ cm sec^-1).

(A) 1.24 x 10¹⁵ sec^-1

(B) 0.24 x 10¹⁵ sec^-1 

(C) 12.4 x 10¹² sec^-1

(D) 2.31 x 10¹⁸ sec^-1

A glow worm of mass 5.0 g emits red light (650 nm) with a power of 0.1 W. entirely in the backward direction. What velocity would it accelerate to after 10 years, if released in free space (and assumed to be alive)?

(a) 9.14 ms^-1 

(b) 28.08 ms^-1

(c) 11.05 ms^-1

(d) 21.04 ms^-1

The rest mass of a proton is 1.673 x 10^-27 kg and that of the electron is 9.109 x 10^-31 kg. What must be the speed of the proton which has the same de Broglie wavelength as an electron moving with a speed of 9 x 10⁶ m/s?

(A) 3600 m/s

(B) 4900 m/s

(C) 4300 m/s

(D) 5600 m/s

The accelerating potential to be imparted to a beam of electrons to give an effective wavelength of 2.42 nm is 

(A) 2.56V

(B) 3.42V

(C) 0.256V

(D) 0.342V

A photon of wavelength 300 nm causes the emission of two photons. If the wavelength of one of them is 700 nm. What is the wavelength of the other photon?

(A) 525 mm

(B) 600 nm

(C) 450 nm

(D) 300 nm