1
JEE Main 2017 (Offline)
+4
-1
Some energy levels of a molecule are shown in the figure. The ratio of the wavelengths r = $${{\lambda _1}}$$/$${{\lambda _2}}$$, is given by:

A
r = 1/3
B
r = 4/3
C
r = 2/3
D
r = 3/4
2
JEE Main 2017 (Offline)
+4
-1
A radioactive nucleus A with a half life T, decays into a nucleus B. At t = 0, there is no nucleus B. At sometime t, the ratio of the number of B to that of A is 0.3. Then, t is given by :
A
$$t = {T \over {\log (1.3)}}$$
B
$$t = T\log (1.3)$$
C
$$t = {T \over 2}{{\log 2} \over {\log 1.3}}$$
D
$$t = T{{\log 1.3} \over {\log 2}}$$
3
JEE Main 2016 (Online) 9th April Morning Slot
+4
-1
A hydrogen atom makes a transition from n = 2 to n = 1 and emits a photon. This photon strikes a doubly ionized lithium atom (z = 3) in excited state and completely removes the orbiting electron. The least quantum number for the excited state of the ion for the process is :
A
2
B
3
C
4
D
5
4
JEE Main 2016 (Offline)
+4
-1
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 radio of decayed number of $$A$$ and $$B$$ nuclei will be:
A
$$1:4$$
B
$$5:4$$
C
$$1:16$$
D
$$4:1$$
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Physics
Mechanics
Electricity
Optics
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
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