1
JEE Main 2016 (Offline)
+4
-1
Out of Syllabus
Half-lives of two radioactive elements $$A$$ and $$B$$ are $$20$$ minutes and $$40$$ minutes, respectively. Initially, the samples have equal number of nuclei. After $$80$$ minutes, the ratio of decayed number of $$A$$ and $$B$$ nuclei will be:
A
$$1:4$$
B
$$5:4$$
C
$$1:16$$
D
$$4:1$$
2
JEE Main 2015 (Offline)
+4
-1
As an electron makes a transition from an excited state to the ground state of a hydrogen - like atom/ion :
A
kinetic energy decreases, potential energy increases but total energy remains same
B
kinetic energy and total energy decrease but potential energy increases
C
its kinetic energy increases but potential energy and total energy decrease
D
kinetic energy, potential energy and total energy decrease
3
JEE Main 2014 (Offline)
+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
$${\lambda _1} = 2{\lambda _2} = 3{\lambda _3} = 4{\lambda _4}$$
4
JEE Main 2014 (Offline)
+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
$$1.6$$ $$eV$$
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Physics
Mechanics
Electricity
Optics
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
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