Carbon-14 has a half-life of 5720 years and this is a first-order reaction. If a piece of wood has converted 88.5% of the carbon-14, then how old is it?

The sample of Carbon-14 isotope is 37056.3 years old

Explanation:

The equation used to calculate rate constant from given half life for first order kinetics:

where,

= half life of the reaction = 5720 years

Putting values in above equation, we get:

Rate law expression for first order kinetics is given by the equation:

where,

k = rate constant  =

t = time taken for decay process = ? yr

= initial amount of the sample = 100 grams

[A] = amount left after decay process =  (100 - 88.5) = 11.5 grams

Putting values in above equation, we get:

Hence, the sample of Carbon-14 isotope is 37056.3 years old

the grams   of   barium that   are in   2.3 x 10^23   atoms of barium   is   52.4 g (answer c)

    calculation

mass = moles   of ba   x molar   mass of ba

  molar mass of ba from periodic table=   137.3 g/mol

  use the   avogadro's law   constant   to   calculate the moles of barium

  that   is     1 mole =   6.02   x 10^23 atoms

                    ? moles = 2.3 x 10^23   atoms

by cross   multiplication

=(1 mole   x 2.3x 10^23 atoms)   / 6.02   x10^23 atoms)=   0.382   moles

mass   is therefore = 137.3   g/mol x 0.382 mol = 52.4 ( answer c)

explanation:

d: the voltage of the secondary coil is less than that of the primary coil.

im not suree sorry if wrong