Why is the Hertzsprung-Russell (H-R) diagram an important tool for astronomers? Select the best answer.

A: it helps them classify stars.

B: it helps them study the life cycle phases of stars.

C: both A and B

D: neither A nor B

Which is the correct order in the scientific process? ask a question ® form a hypothesis ® make an observation ask a question ® make an observation ® form a hypothesis make an observation ® form a hypothesis ® ask a question make an observation ® ask a question ® form a hypothesis

Achild is suffering from fever but the doctor cannot immediately pinpoint the alignment on the basis of this one symptom explain why also mention other two such general symptoms

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