1
AIEEE 2011
+4
-1
Out of Syllabus
The half life of a radioactive substance is $$20$$ minutes. The approximate time interval $$\left( {{t_2} - {t_1}} \right)$$ between the time $${{t_2}}$$ when $${2 \over 3}$$ of it had decayed and time $${{t_1}}$$ when $${1 \over 3}$$ of it had decayed is :
A
$$14$$ min
B
$$20$$ min
C
$$28$$ min
D
$$7$$ min
2
AIEEE 2010
+4
-1
A nucleus of mass $$M+$$$$\Delta m$$ is at rest and decays into two daughter nuclei of equal mass $${M \over 2}$$ each. Speed of light is $$c.$$

The binding energy per nucleon for the parent nucleus is $${E_1}$$ and that for the daughter nuclei is $${E_2}.$$ Then

A
$${E_2} = 2{E_1}$$
B
$${E_1} > {E_2}$$
C
$${E_2} > {E_1}$$
D
$${E_1} = 2{E_2}$$
3
AIEEE 2010
+4
-1
A nucleus of mass $$M+$$$$\Delta m$$ is at rest and decays into two daughter nuclei of equal mass $${M \over 2}$$ each. Speed of light is $$c.$$

The speed of daughter nuclei is

A
$$c{{\Delta m} \over {M + \Delta m}}$$
B
$$c\sqrt {{{2\Delta m} \over M}}$$
C
$$c\sqrt {{{\Delta m} \over M}}$$
D
$$c\sqrt {{{\Delta m} \over {M + \Delta m}}}$$
4
AIEEE 2010
+4
-1
Out of Syllabus
A radioactive nucleus (initial mass number $$A$$ and atomic number $$Z$$ emits $$3\,\alpha$$- particles and $$2$$ positrons. The ratio of number of neutrons to that of protons in the final nucleus will be
A
$${{A - Z - 8} \over {Z - 4}}$$
B
$${{A - Z - 4} \over {Z - 8}}$$
C
$${{A - Z - 12} \over {Z - 4}}$$
D
$${{A - Z - 4} \over {Z - 2}}$$
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