1
JEE Main 2022 (Online) 27th June Morning Shift
Numerical
+4
-1

A beam of monochromatic light is used to excite the electron in Li+ + from the first orbit to the third orbit. The wavelength of monochromatic light is found to be x $$\times$$ 10$$-$$10 m. The value of x is ___________.

[Given hc = 1242 eV nm]

2
JEE Main 2022 (Online) 24th June Evening Shift
Numerical
+4
-1

A sample contains 10$$-$$2 kg each of two substances A and B with half lives 4 s and 8 s respectively. The ratio of their atomic weights is 1 : 2. The ratio of the amounts of A and B after 16 s is $${x \over {100}}$$. The value of x is ___________.

3
JEE Main 2021 (Online) 27th August Evening Shift
Numerical
+4
-1
X different wavelengths may be observed in the spectrum from a hydrogen sample if the atoms are exited to states with principal quantum number n = 6 ? The value of X is ______________.
4
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 $${{22} \over 7}$$]
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