Roboguru

Sebanyak 2 gram radioaktif   mempunyai aktivitas mula-mula . Jika setelah meluruh selama 44 hari, massanya tersisa 0,5 gram, besar aktivitas radioaktif adalah...

Pertanyaan

Sebanyak 2 gram radioaktif  begin mathsize 14px style Cr presubscript 24 presuperscript 48 end style mempunyai aktivitas mula-mula begin mathsize 14px style 0 comma 02 space mu Ci end style. Jika setelah meluruh selama 44 hari, massanya tersisa 0,5 gram, besar aktivitas radioaktif adalah... 

  1. begin mathsize 14px style 0 comma 100 space mu Ci end style 

  2. size 14px 0 size 14px comma size 14px 050 size 14px space size 14px mu size 14px Ci 

  3. size 14px 0 size 14px comma size 14px 010 size 14px space size 14px mu size 14px Ci 

  4. size 14px 0 size 14px comma size 14px 005 size 14px space size 14px mu size 14px Ci 

  5. size 14px 0 size 14px comma size 14px 001 size 14px space size 14px mu size 14px Ci 

Pembahasan Soal:

Diketahui:
begin mathsize 14px style Cr presubscript 24 presuperscript 48 end style 

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell N subscript o end cell equals cell space 2 space gr end cell row cell A subscript o end cell equals cell 0 comma 02 space μCi space equals space 0 comma 02 cross times 10 to the power of negative 6 end exponent Ci end cell row cell t space end cell equals cell space 44 space hari end cell row cell N subscript t space end cell equals cell space 0 comma 5 space straight g end cell end table end style  

Ditanya:
A = ?

Jawab

(i) Hitung n

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell N subscript t space end cell equals cell space N subscript o left parenthesis 1 half right parenthesis to the power of n space end cell row cell 0 comma 5 space end cell equals cell space 2 space left parenthesis 1 half right parenthesis to the power of n space end cell row cell 1 fourth end cell equals cell space left parenthesis 1 half right parenthesis to the power of n space end cell row cell left parenthesis 1 half right parenthesis squared end cell equals cell space left parenthesis 1 half right parenthesis to the power of n space end cell row cell n space end cell equals cell space 2 end cell end table end style   

(ii) Menghitung aktivitas radioaktif
begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell A subscript t end cell equals cell A subscript o left parenthesis 1 half right parenthesis to the power of n end cell row cell space A subscript t end cell equals cell 0 comma 02 cross times 10 to the power of negative 6 end exponent left parenthesis 1 half right parenthesis squared space end cell row blank equals cell 5 cross times 10 to the power of negative 9 end exponent space Ci end cell end table end style  

Jadi, jawaban yang benar adalah D

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 19 Mei 2021

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