An original sample of k-40 has a mass of 25.00 grams. after 3.9 × 109 years, 3.125 grams of the original sample remains unchanged. what
is the half-life of k-40?
(1) 1.3 × 109 y (3) 3.9 × 109 y
(2) 2.6 × 109 y (4) 1.2 × 1010 y

La respuesta correcta es

Explanation:

Hello! Let's solve this!

First we have to know the mass / mass exponent without changes

The data is:

m = 25 g

mc (mass without changes) = 3.125g

25 / 3,125 = 8 =

The exponent is 3, so we divide the number of years by three.

La respuesta correcta es

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current