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.(92)^(238)U atom distintgrates to .(84)...

`._(92)^(238)U` atom distintgrates to `._(84)^(214) Po` with a half life of `4.5xx10^(9)` years by emitting six alpha particles and n electrons. Here n is -

A

6

B

4

C

10

D

7

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The correct Answer is:
B
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The nucleus ._(92)U^(238) is unstable angainst alpha decay with half-life of 4.5 xx 10^(9) years. Estimate the kinetic energy of the emitted alpha -particle. Mass of the ._(92)U^(238) atom = 238.05081 u Mass of the ._(2)He^(4) atom = 4.00260 u Mass of the ._(90)Th^(234) atom = 234.04363 u

The radioactive substance ""_(92)U^(238) has a half-life of 4.5 xx 10^(9) years. Determine the time taken for 3/4 of the substance to disintegrate.

(a) On analysis a sample of uranium ore was found to contian 0.277g of ._(82)Pb^(206) and 1.667g of ._(92)Pb^(206) and 1.667g of ._(92)U^(238) . The half life period of U^(238) is 4.51xx10^(9) year. IF all the lead were assumed to have come from decay of ._(92)U^(238) , What is the age of earth? (b) An ore of ._(92)U^(238) is found to contain ._(92)U^(238) and ._(82)Pb^(206) in the weight ratio of 1: 0.1 The half-life period of ._(92)U^(238) is 4.5xx10^(9) year. Caluculate the age of ore.

.^(238)U decays with a half-life of 4.5 xx10^(9) years, the decay series eventaully ending at .^(206)Pb , which is stable. A rock sample analysis shows that the ratio of the number of atoms of .^(206)Pb to .^(238)U is 0.0058. Assuming that all the .^(206)Pb is prodduced by the decay of .^(238)U and that all other half-lives on the chain are negligilbe, the age of the rock sample is (1n 1.0058 =5.78 xx10^(-3)) .

On analysis a sample of .^(238)U ore was found to contain 20.6g of ._(82)^(206)Pb ad 23.8g of ._(92)^(238)U . The half life period .^(238)U is 4.50 xx 10^(9) years. If all the lead were assumed to have come from decay of ._(92)^(238)U , what is the age of the ore?

The atomic ratio between the uranium isotopes .^(238)U and.^(234)U in a mineral sample is found to be 1.8xx10^(4) . The half life of .^(234)U is T_((1)/(2))(234)=2.5xx10^(5) years. The half - life of .^(238)U is -

On analysis a sample of uranium are was found to contain 227g of ._(82)Pb^(208) and 1.667 g of ._(92)U^(238) . The half life peiod of U^(238) is 4.51 xx 10^(9) yrs. If all the lead was assumed to have come from decay of ._(92)U^(238) , what is the age of the earth?

._(92)U^(238) is radioactive and it emits alpha and beta particles to form ._(82)Pb^(206). Calculate the number of alpha and beta particles emitted in this conversion. An ore of ._(92)U^(238) is found ot contain ._(92)U^(238) and _(82)Pb^(206) in the weight ratio of 1: 0.1. The half- life -period of ._(92)U^(238) is 4.5xx 10^(9) yr. Calculate the age of the ore.

Nucleus ._(92)U^(238) emits alpha -particle (._(2)He^(4)) . alpha- particle has atomic number 2 and mass number 4. At any instant alpha- particle is at distance of 9 xx 10^(-15)m from the centre of nucleus of uranium. What is the force on alpha- particle at this instant? ._(92)U^(238) rarr ._(2)He^(4) + ._(90)Th^(234)

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