Question

1.) What is the missing particle?

$_{92}^{238}U+ 17_{1}^{0}n\rightarrow +8_ {-1}^{0}\beta$

2.) Carbon-14 decays by beta emission and has a half-life of 5,730 years

a.) Write the balanced equation for this reaction.

b.) What percentage of a $_{}^{14}C$ sample remains after 3,310 years?

3.) Bismuth-214 is an a-emitter with a half-life of 19.7 min. How long does it take for 75.0% of $_{}^{214}Bi$ to decay?

Answer 1

Missing particle suppose missing particle is m so, suppose missing particle is x so, Total number of protons on Reactants = 92 + 17 (1) 109 Total atomic mass of reactants = 238 + 0 = 238 Total number of protons & atomic mass should be base on both sides so, on product side number of protons = x + 8 (-1) = x -8 x -8 = 109 x = 109 + 8 = 117 Atomic mass y + 8(0) = y y = 238 so, missing particle is 117 According to periodic table the element with 117 protons is uses so, missing particle is 2). 14_C decays with t_1/2 = 5730 years b). t_1/2 = 5730 years so, In 5730 years no of half lives = 1 After 3310 years Number of half lives elapsed = 3310/5730 = 0.577 so, suppose initially amount of 14_C_0.577 = 100 g so, of the 3310 years 100 (1/2) = 679