A sample contains two isotopes -one stale and the other unstable. Number of stable nuclei is equal to `N_(s)` and number of unstable nuclei is equal to `N_(u)`. After a time the activity of the sample decreased to one thrid of the, the initial activity while the total number of nuclei (excluding decayed nuclei) became half. find the initial value of the ratio `N_(s)//N_(u)`.
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A chalk sample exactly 17.52 gram HCl for complete reaction with all `CaCO_(3)` present in it. If the chalk sample is 72% pure, the mass of sample tak
`CaCO_(3) + 2HCl to CaCl_(2) + H_(2)O+CO_(2)` Moles of HCl `=(17.52)/(36.5)` Moles of `CaCo_(3)=(1)/(2)xx(17.52)/(36.5)` Weight of `CaCO_(3)` required `=(1)/(2)xx(17.52)/(36.5)xx100` Mass of sample taken: `=(1)/(2) xx(17.52)/(36.5)xx(100xx100)/(72)=33.33` gm
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An impure sample of calcium carbon contains 80% pure of impure sample reacted with excess of hydrochloric acid. Calculate the volume of carbon dioxide
100g of impure of calcium carbonate contain=80g pure of calcium carbonate 25g impure calcium carbonate sample contain `=(80)/(100)xx25` =20g of pure calcium carbonate The desired equation is `underset(100g)underset(1"mol")(CaCO_(3))+2HCl to CaCl_(2)+underset("at...
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A sample of oxygen contains `O^(16) & O^(18)` isotopes only with percentage abundance respectively as 90% & 10% in terms of mole. Identify the correct
Correct Answer - A::B::D (A) Average atomic mass `=(M_(1)n_(1)+M_(2)n_(2))/(n_(1)+n_(2))=(16xx90+18xx10)/(100)=16.2` (B) Average number of protons `=(8xx90+8xx10)/(100)=8` (C ) Average number of neutrons `=(8xx90+10xx10)/(100)=8.2`
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Hydrogen like atoms (atomic number `= Z`) in a sample are in excited state with principal quantum number n. The emission spectrum of the sample has `1
Correct Answer - `Z = 3`
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Which of the following isotopes is more stable and why? (a) `._(3)^(7)Li` or `._(3)^(8)Li` (b) `._(6)^(13)C` or `_(6)^(15)C` (c) What kind of decay wi
Correct Answer - (a) `._(3)^(7)Li` (b) `._(6)^(13)C` (c) `._(3)^(8)Lirarr` negaive `beta` decay; `._(6)^(15)Crarr` negative `beta` decay
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A radioactive sample consists of two isotopes one of then decays by `alpha-` emission with a half life of `tau_(1)=405s` and the other one decays by `
Correct Answer - (a) `(1)/(9)` (b) 1215s
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The half lives of two longest-lived radioactive isotopes of phosphorus `P^(32)` and `P^(33)`, are 14 days and 28 days respectively. A sample has been
Correct Answer - 0.3mCi
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A rock sample has radioactive isotope A that decays into a stable product B. half life of A is `10^(3)` year. It was found that the rock sample contai
Correct Answer - 680y
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A sample of Uranium is a mixture of two isotopes `._(92)^(234)U` and `._(92)^(238)U` present in the ratio `10%` and `90%` by weight. The half lives of
Correct Answer - `[16.67% and 83.33 %]`
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A solution contains a mixture of two isotopes A (`half-life=10days`) and B (`half-life=5days`). Total activity of the mixture is `10^10` disintegratio
Correct Answer - `[(a) 0.73xx10^(10) dps 0.27xx10^(10) dps, (b) 5.4]`
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