What are the hard parts of life forms found in rocks called?

The age of a fossil is determined by

Which of the following is a connecting link between reptiles and birds?

Which of the following statements is correct?

Separate the following into homologous and analogous organs:
$I.$ Sweet potato
$II.$ Potato
$III.$ Flippers of penguins and dolphins
$IV.$ Hearts of different vertebrates
$V.$ Forelimbs of whales,bats,and cheetahs
The correct option is:

Define the following terms: $Fossil$ and $Geological$ $time$.