1
JEE Main 2017 (Online) 9th April Morning Slot
+4
-1
The acceleration of an electron in the first orbit of the hydrogen atom (n = 1) is :
A
$${{{h^2}} \over {{\pi ^2}{m^2}{r^3}}}$$
B
$${{{h^2}} \over {{8\pi ^2}{m^2}{r^3}}}$$
C
$${{{h^2}} \over {{4\pi ^2}{m^2}{r^3}}}$$
D
$${{{h^2}} \over {{4\pi }{m^2}{r^3}}}$$
2
JEE Main 2017 (Online) 9th April Morning Slot
+4
-1
Imagine that a reactor converts all given mass into energy and that it operates at a power level of 109 watt. The mass of the fuel consumed per hour in the reactor will be : (velocity of light, c is 3×108 m/s)
A
0.96 gm
B
0.8 gm
C
4 $$\times$$ 10$$-$$2 gm
D
6.6 $$\times$$ 10$$-$$5 gm
3
JEE Main 2017 (Online) 8th April Morning Slot
+4
-1
According to Bohr’s theory, the time averaged magnetic field at the centre (i.e. nucleus) of a hydrogen atom due to the motion of electrons in the nth orbit is proportional to : (n = principal quantum number)
A
$${n^{ - 4}}$$
B
$${n^{ - 5}}$$
C
n$$-$$3
D
n$$-$$2
4
JEE Main 2017 (Online) 8th April Morning Slot
+4
-1
Two deuterons undergo nuclear fusion to form a Helium nucleus. Energy released in this process is : (given binding energy per nucleon for deuteron = 1.1 MeV and for helium = 7.0 MeV)
A
30.2 MeV
B
32.4 MeV
C
23.6 MeV
D
25.8 MeV
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