1
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
Hydrogen $$\left( {{}_1{H^1}} \right)$$, Deuterium $$\left( {{}_1{H^2}} \right)$$, singly ionised Helium $${\left( {{}_2H{e^4}} \right)^ + }$$ and doubly ionised lithium $${\left( {{}_3L{i^6}} \right)^{ + + }}$$ all have one electron around the nucleus. Consider an electron transition from $$n=2$$ to $$n=1.$$ If the wavelengths of emitted radiation are $${\lambda _1},{\lambda _2},{\lambda _3}$$ and $${\lambda _4}$$ respectively then approximately which one of the following is correct?
A
$$4{\lambda _1} = 2{\lambda _2} = 2{\lambda _3} = {\lambda _4}$$
B
$${\lambda _1} = 2{\lambda _2} = 2{\lambda _3} = {\lambda _4}$$
C
$${\lambda _1} = {\lambda _2} = 4{\lambda _3} = 9{\lambda _4}$$
D
$${\lambda _1} = 2{\lambda _2} = 3{\lambda _3} = 4{\lambda _4}$$
2
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
The radiation corresponding to $$3 \to 2$$ transition of hydrogen atom falls on a metal surface to produce photoelectrons. These electrons are made to enter a magnetic field $$3 \times {10^{ - 4}}\,T.$$ If the radius of the larger circular path followed by these electrons is $$10.0$$ $$mm$$, the work function of the metal is close to:
A
$$1.8$$ $$eV$$
B
$$1.1$$ $$eV$$
C
$$0.8$$ $$eV$$
D
$$1.6$$ $$eV$$
3
JEE Main 2013 (Offline)
MCQ (Single Correct Answer)
+4
-1
In a hydrogen like atom electron make transition from an energy level with quantum number $$n$$ to another with quantum number $$\left( {n - 1} \right)$$. If $$n > > 1,$$ the frequency of radiation emitted is proportional to :
A
$${1 \over n}$$
B
$${1 \over {{n^2}}}$$
C
$${1 \over {{n^{{3 \over 2}}}}}$$
D
$${1 \over {{n^3}}}$$
4
AIEEE 2012
MCQ (Single Correct Answer)
+4
-1
Assume that a neutron breaks into a proton and an electron. The energy released during this process is : (mass of neutron $$ = 1.6725 \times {10^{ - 27}}kg,$$ mass of proton $$ = 1.6725 \times {10^{ - 27}}\,kg,$$ mass of electron $$ = 9 \times {10^{ - 31}}\,kg$$ ).
A
$$0.51$$ $$MeV$$
B
$$7.10\,MeV$$
C
$$6.30\,MeV$$
D
$$5.4\,MeV$$
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