Tritium has a half-life of 12.33 years. What fraction of the nuclei in a tritium sample will remain (a) after 5.00 yr? (b) After 10.0 yr? (c) After 123.3 yr? (d) According to Equation 29.4a, an infinite amount of time is required for the entire sample to decay. Discuss whether that is realistic.

Complete each of the following nuclear reaction equations: (a)23592U + 10 n ---> 14156Ba + _____ (formula) + 3 10n (b)23892U ---> 23490Th + ________ ( formula and name) (c)3015P ---> 3014Si + _______ (formula and name) (d) 22888Ra ---> 22889Ac + ______ (formula and name)

Half life of a radioactive isotope is 4x10³ years. If there are 10³ radioactive nudei in a sample today, the number of such nuclei in the sample 4x10⁹ year ago were: (A)128 X10³ (B) 256X10³ (C) 512 X10³ (D) 1024 X10³

All the very heavy atoms found in the earth were created long ago by nuclear fusion reactions in a supernova, an exploding star. The debris spewed out by the supernova later coalesced to form the sun and the planets of our solar system. Nuclear physics suggests that the uranium isotopes 235U (t1/2 = 7.04 × 108 yr) and 238U (t1/2 = 4.47 × 109 yr) should have been created in roughly equal amounts. Today, 99.28% of uranium is 238U and 0.72% is 235U. How long ago did the supernova occur?

b) Complete the following decay reaction by identifying both the temporary nucleus (??) and the end product (?) that it decays into. In this case, sodium-23 is bombarded with protons, forming a short-lived nucleus which quickly undergoes alpha decay. 2Na+H → (??) → (⁄?) + ª Enter the chemical symbol for the temporary nucleus: Enter the mass number for the end product, A = Enter the atomic number for the end product, Z = Enter the chemical symbol for the end product: AV A/ AV 10

Question 1. Tritium has a half - life of 12.33 years. What fraction of the nuclei in a tritium sample will remain (a) after 5.00 yr? (b) after 10.0 yr? (с) after 123.3 yг?

Two radioactive isotopes, X and Y, both decay to stable products. The half-life of X is about aday, while that of Y is about a week. Suppose a radioactive sample consists of a mixture of thesetwo nuclides. If the mixture is such that the activities arising from X and Y are initially equal,then a few days later the activity of the sample will be due ………………………………… .i. predominantly to X.ii. predominantly to Y.iii. to X and Y equally.iv. entirely to Y.

Potassium-argon dating is used to measure the age of rocks formed from cooled lava by determining the fraction of the original 40K remaining in a sample from the ratio of 40K:40Ar. Unusually, potassium-40 decays into both 40Ca (89.1% of the time) and 40Ar (10.9% of the time) with a half-life of 1:248 x 10^9 years. 1. Write out balanced nuclear equations for these two decay processes. 2. Calculate the specific activity of 40K.

The half-life of beryllium-7 is about 53.3 days. (a) Determine the decay constant for beryllium-7. (b) What percentage of a sample remains undecayed after two weeks (1.21 ✕ 106 s)?

What is the half‑life of an isotope that decays to 6.25%6.25% of its original activity in 24.2 h?24.2 h? half‑life: