JEE Main 2019 (Online) 12th January Evening Slot | Structure of Atom Question 123 | Chemistry

If the de Broglie wavelength of the electron in n^th Bohr orbit in a hydrogenic atom is equal to 1.5 $$\pi $$a₀ (a₀ is Bohr radius), then the value of n/z is -

0.75

0.40

1.50

1.0

JEE Main 2019 (Online) 12th January Evening Slot

MCQ (Single Correct Answer)

-1

The upper stratosphere consisting of the ozone layer protects us from sun's radiation that falls in the wavelength region of -

200-315 nm

400-550 nm

0.8-1.5 nm

600-750 nm

JEE Main 2019 (Online) 12th January Morning Slot

MCQ (Single Correct Answer)

-1

What is the work function of the metal if the light of wavelength 4000$$\mathop A\limits^ \circ $$ generates photoelectrons of velocity 6 $$ \times $$ 10⁵ ms^–1 from it ?
(Mass of electron = 9 $$ \times $$ 10^–31 kg;
Velocity of light = 3 $$ \times $$ 10⁸ ms^$$-$$1
Plank's constant = 6.626 $$ \times $$ 10^–34 Js;
Charge of electron = 1.6 $$ \times $$10^–19 JeV^–1)

4.0 eV

0.9 eV

2.1 eV

3.1 eV

JEE Main 2019 (Online) 11th January Evening Slot

MCQ (Single Correct Answer)

-1

The de Broglie wavelength ($$\lambda $$) associated with a photoelectron varies with the frequency (v) of the incident radiation as, [v₀ is threshold frequency] :

$$\lambda \,\infty \,{1 \over {{{\left( {v - {v_0}} \right)}^{{3 \over 2}}}}}$$

$$\lambda \,\infty \,{1 \over {{{\left( {v - {v_0}} \right)}^{{1 \over 4}}}}}$$

$$\lambda \,\infty \,{1 \over {\left( {v - {v_0}} \right)}}$$

$$\lambda \,\infty \,{1 \over {{{\left( {v - {v_0}} \right)}^{{1 \over 2}}}}}$$

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