1
JEE Main 2021 (Online) 27th July Evening Shift
Numerical
+4
-1
The K$$\alpha$$ X-ray of molybdenum has wavelength 0.071 nm. If the energy of a molybdenum atoms with a K electron knocked out is 27.5 keV, the energy of this atom when an L electron is knocked out will be __________ keV. (Round off to the nearest integer)

[h = 4.14 $$\times$$ 10$$-$$15 eVs, c = 3 $$\times$$ 108 ms$$-$$1]
2
JEE Main 2021 (Online) 27th July Morning Shift
Numerical
+4
-1
In Bohr's atomic model, the electron is assumed to revolve in a circular orbit of radius 0.5 $$\mathop A\limits^o$$. If the speed of electron is 2.2 $$\times$$ 166 m/s, then the current associated with the electron will be _____________ $$\times$$ 10$$-$$2 mA. [Take $$\pi$$ as $${{22} \over 7}$$]
3
JEE Main 2021 (Online) 27th July Morning Shift
Numerical
+4
-1
Out of Syllabus
A radioactive sample has an average life of 30 ms and is decaying. A capacitor of capacitance 200 $$\mu$$F is first charged and later connected with resistor 'R'. If the ratio of charge on capacitor to the activity of radioactive sample is fixed with respect to time then the value of 'R' should be _____________ $$\Omega$$.
4
JEE Main 2021 (Online) 25th July Evening Shift
Numerical
+4
-1
From the given data, the amount of energy required to break the nucleus of aluminium $$_{13}^{27}$$Al is __________ x $$\times$$ 10$$-$$3 J.

Mass of neutron = 1.00866 u

Mass of proton = 1.00726 u

Mass of Aluminium nucleus = 27.18846 u

(Assume 1 u corresponds to x J of energy)

(Round off to the nearest integer)