An isotope of Potassium `._(19)^(40) K ` has a half life of `1.4 xx 10^(9)`year and decays to Argon `._(18)^(40)Ar`which is stable. (i) Write down the nuclear reaction representing this decay. (ii) A sample of rock taken from the moon contains both potassium and argon in the ratio `1//3`. find age of rock

An isotope of Potassium `._(19)^(40) K ` has a half life of `1.4 xx 10

1.	An isotope of Potassium `._(19)^(40) K ` has a half life of `1.4 xx 10^(9)`year and decays to Argon `._(18)^(40)Ar`which is stable. (i) Write down the nuclear reaction representing this decay. (ii) A sample of rock taken from the moon contains both potassium and argon in the ratio `1//3`. find age of rock
Answer» Correct Answer - (i) `._(19)^(40) K rarr . _(18)^(40) Ar + ._(+1) beta ^(0) +v` (i) `._(19)^(40)Krarr._(18)^(40)Ar+.._(+1)" "^(0)e` (positron) (ii) `t=(1)/(lambda) ln .(1)/((1//4))" " (K)/(Ar)=(1)/(3)` (Given ratio) `=(1.4 xx10^(9))/(ln2) ln4 " " k=((1)/(4))` `=2.8 xx 10^(9)` years

Discussion

No Comment Found

Related InterviewSolutions

Calculate the equivalent weight of each oxidant and reducant in: (a) `FeSO_(4) + KCl_(3) rarr KCl + Fe_(2) (SO_(4))_(3)` (b) `Na_(2) SO_(3) + Na_(2)CrO_(4) rarr Na_(2) CrO_(4) rarr Na_(2) SO_(4) + Cr(OH)_(3)` (c) `Fe_(3)O_(4) + KMnO_(4) rarr Fe_(2) O_(3) + MnO_(2)` (d) `KI + K_(2) Cr_(2) O_(7) rarr Cr^(3+) + 3I_(2)` (e) `Mn^(4+) rarr Mn^(2+)` (f) `NO_(3)^(-) rarr N_(2)` (g) `N_(2) rarr NH_(3)` (h) `Na_(2) S_(2) O_(3) + I_(2) rarr Na_(2) S_(4) O_(6) + 2NaI` (i) `FeC_(2)O_(4) rarr Fe^(3+) + CO_(2)`
In the reaction `Al + Fe_(3)O_(4) rarr Al_(2) O_(3) + Fe` (a) Which element is oxidized and which is reduced? (b) Total no. of elecetros transferred during the change.
If `m_(p)` and `m_(n)` are masses of proton and neutron respectively and `M_(1)` and `M_(2)` are masses of `._(10)MeNe^(20)` and `._(20)Ca^(40)` nucleus repectively, then:A. `M_(2) = 2M_(1)`B. `M_(2) lt 2M_(1)`C. `M_(2) gt 2M_(1)`D. `M_(1) lt 10(m_(n) + m_(p))`
The intergrated rate equation is `Rt = log, C_(0) - log C_(t)`. The straight line graph is obtained by plotting:A. `t` vs log `C_(t)`B. `(1)/(t)` vs log `C_(t)`C. `t` vs `C_(t)`D. `(1)/(t)` vs log `(1)/(C_(t))`
The half life of `.^(215)At` is `100mu s`. The time taken for the radioacticity of `.^(215)At` to decay to `1//16^(th)` of its initial value is:A. `400mu s`B. `6.3mu s`C. `40mu s`D. `300mu s`
The half life period of `._(53)I^(125)` is 60 days. What % of radioactivity would be present after 240 days.
The disntergration rate of a certain radioactive sample at any instant is `4750 dp m`. Five minute later, the rate becomes `2700 dp m` Calculate half-line of sample.
Two elements `P` and `Q` have half-line of `10` and `15` minutes repectively. Freshly preapared sample of mixuture containing equal number of atoms is allowed to decay for `30` minutes. The ratio of number of atoms of `P` and `Q` in left in mixture is:A. `0.5`B. `2.0`C. `3.0`D. `4.0`
`KMnO_(4)` oxidises `NO_(2)^(-)` to `NO_(3)^(-)` in basic medium. How many moles of `NO_(2)^(-)` are oxidised by `1 mol` of `KMnO_(4)`?
A freshly prepared radioactive source to half-life `2 hr`, emits radiatiosn of intensity which is 64 times the permissible safe level. The minumum time after which it would be possibleto work safely with the source is:A. `6 hr`B. `12 hr`C. `24 hr`D. `128 hr`

Discussion

No Comment Found

Related InterviewSolutions

Reply to Comment