1
NEET 2013
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
The half life of a radioactive isotope 'X' is 20 years. It decays to another element 'Y' which is stable. The two elements 'X' and 'Y' were found to be in the ratio 1 : 7 in a sample of a given rock. The age of the rock is estimated to be
A
80 years
B
100 years
C
40 years
D
60 years
2
AIPMT 2012 Mains
MCQ (Single Correct Answer)
+4
-1
Change Language
The transition from the state n = 3 to n = 1 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from
A
2 $$ \to $$ 1
B
3 $$ \to $$ 2
C
4 $$ \to $$ 2
D
4 $$ \to $$ 3
3
AIPMT 2012 Mains
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
The half life of a radioactive nucleus is 50 days. The time invertal (t2 $$-$$ t1) between the time t2 when $${2 \over 3}$$ of it has decayed and the time t1 when $${1 \over 3}$$ of it had decayed is
A
30 days
B
50 days
C
60 days
D
15 days
4
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
A mixture consists of two radioactive materials A1 and A2 with half lives of 20 s and 10 s respectively. Initially the mixture has 40 g of A1 and 160 g of A2. The amount of the two in the mixture will become equal after
A
60 s
B
80 s
C
20 s
D
40 s
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