1
JEE Main 2021 (Online) 26th February Evening Shift
Numerical
+4
-1
Change Language
A ball weighing 10 g is moving with a velocity of 90 ms$$-$$1. If the uncertainty in its velocity is 5%, then the uncertainty in its position is ___________ $$\times$$ 10$$-$$33 m. (Rounded off to the nearest integer)

[Given : h = 6.63 $$\times$$ 10$$-$$34 Js]
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2
JEE Main 2021 (Online) 25th February Evening Shift
Numerical
+4
-1
Change Language
Electromagnetic radiation of wavelength 663 nm is just sufficient to ionise the atom of metal A. The ionization enegy of metal A in kJ mol$$-$$1 is __________. (Rounded off to the nearest integer)

[h = 6.63 $$\times$$ 10$$-$$34 Js, c = 3.00 $$\times$$ 108 ms$$-$$1, NA = 6.02 $$\times$$ 1023 mol$$-$$1]
Your input ____
3
JEE Main 2021 (Online) 25th February Evening Shift
Numerical
+4
-1
Change Language
Among the following, number of metal/s which can be used as electrodes in the photoelectric cell is _________. (Integer answer)

(A) Li

(B) Na

(C) Rb

(D) Cs
Your input ____
4
JEE Main 2021 (Online) 24th February Morning Shift
Numerical
+4
-1
Change Language
A proton and a Li3+ nucleus are accelerated by the same potential. If $$\lambda _{Li}$$ and $$\lambda _p$$ denote the de Broglie wavelengths of Li3+ and proton respectively, then the value of $${{{\lambda _{Li}}} \over {{\lambda _p}}}$$ is x $$ \times $$ 10-1.
The value of x is ______. (Rounded off to the nearest integer)
[Mass of Li3+ = 8.3 mass of proton]
Your input ____
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