The c-14 decay is used to estimate the age of an old dead tree. the activity of c-14 in the dead tree is determined to have fallen to 21% of its original value. c-14 has a half-life of 5700 years. calculate, in years, the age of the dead tree.
i used the relevant formula but somehow my answer does not match with the markscheme. can you me?

cell differentiation  is how generic embryonic  cells  become specialized  cells. this occurs  through a process called gene expression. gene expression is the specific combination of genes that are turned on or off (expressed or repressed), and this is what dictates how a  cell  functions.

explanation:

choosing tennis and golf balls is your inde choice.

their mass and volume are dep