1
JEE Main 2018 (Online) 15th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The energy required to remove the electron from a singly ionized Helium atom is $$2.2$$ times the energies required to remove an electron from Helium atom. The total energy required to ionize the Helium atom completely is :
A
$$20$$ $$eV$$
B
$$34$$ $$eV$$
C
$$79$$ $$eV$$
D
$$109$$ $$eV$$
2
JEE Main 2018 (Online) 15th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
A solution containing active cobalt $${^{60}_{27}}Co$$ having activity of $$0.8$$ $$\mu Ci$$ and decay constant $$\lambda $$ is injected in an animal's body. If $$1\,c{m^3}$$ of blood is drawn from the animal's body after $$10$$ hrs of injection, the activity found was $$300$$ decays per minute What is the volume of blood that is flowing in the body ? $$\left( {\,\,Ci = 3.7 \times {{10}^{10}}\,} \right.$$ decays per second and at $$t=10$$ hrs $$\left. {{e^{ - \lambda t}} = 0.84} \right)$$
A
$$6$$ liters
B
$$7$$ liters
C
$$4$$ liters
D
$$5$$ liters
3
JEE Main 2017 (Online) 9th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
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
$${{{h^2}} \over {{4\pi }{m^2}{r^3}}}$$
4
JEE Main 2017 (Online) 9th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
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
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