Which of the following are true?

a. primary succession begins in an area that does not have soil.

b. secondary succession occurs in an area that already had life and soil.

c. primary succession begins in an area that did not have life before.

d. all of these are true.

What makes the results of a scientific experiment accurate? a) having multiple trials b) lacking any supporting data c) working in a lab d) using a hypothesis that is always true

Pentane with molecular formula c5h12, exists in three isomeric forms. one shows linear carbon chains, another has one -ch3 groups present on the third carbon atom, and the third has two -ch3 groups present on the second carbon atom. what types of isomers are these? a. geometric isomers b. structural isomers c. halotropic isomers

Plz quick a natural resource that is replaceable through a cycle in nature or sustainable practice is called a? the subject is science