1
JEE Main 2022 (Online) 24th June Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The light of two different frequencies whose photons have energies 3.8 eV and 1.4 eV respectively, illuminate a metallic surface whose work function is 0.6 eV successively. The ratio of maximum speeds of emitted electrons for the two frequencies respectively will be :

A
1 : 1
B
2 : 1
C
4 : 1
D
1 : 4
2
JEE Main 2022 (Online) 24th June Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Nucleus A is having mass number 220 and its binding energy per nucleon is 5.6 MeV. It splits in two fragments 'B' and 'C' of mass numbers 105 and 115. The binding energy of nucleons in 'B' and 'C' is 6.4 MeV per nucleon. The energy Q released per fission will be :

A
0.8 MeV
B
275 MeV
C
220 MeV
D
176 MeV
3
JEE Main 2021 (Online) 1st September Evening Shift
MCQ (Single Correct Answer)
+4
-1
The temperature of an ideal gas in 3-dimensions is 300 K. The corresponding de-Broglie wavelength of the electron approximately at 300 K, is :

[me = mass of electron = 9 $$\times$$ 10$$-$$31 kg, h = Planck constant = 6.6 $$\times$$ 6.6 $$\times$$ 10$$-$$34 Js, kB = Boltzmann constant = 1.38 $$\times$$ 10$$-$$23 JK$$-$$1]
A
6.26 nm
B
8.46 nm
C
2.26 nm
D
3.25 nm
4
JEE Main 2021 (Online) 1st September Evening Shift
MCQ (Single Correct Answer)
+4
-1
The half life period of radioactive element x is same as the mean life time of another radioactive element y. Initially they have the same number of atoms. Then :
A
x-will decay faster than y.
B
y-will decay faster than x.
C
x and y have same decay rate initially and later on different decay rate.
D
x and y decay at the same rate always.
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