ICSE Class 10 Physics 2016 Solved Paper

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Question : 23
Total: 73
An element ZSA decays to 85R222 after emitting 2α particles and 1β particle. Find the atomic number and atomic mass of the element S.
Solution:  
On emission of 2 alpha particles, mass number is reduced by 8 and atomic number by 4 .
zSAz4QA8+22He4
Now, on emission of 1 beta particle, mass number remains same but atomic number increases by 1 .
z4QA8Z3RA8+10β
After decay, given element is 85R222. Therefore
A8=222A=230
(Atomic Mass)
Z3=85Z=88
(Atomic No.)
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