Through which material can light waves travel but sound waves cannot travel?

Each pair of clay balls represents two planetesimals. if each planetesimal is composed of the same material and is separated he the same distance, which pair experiences the frayed gravitational attraction?

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

People with one sickle cell allele are not likely to get malaria. what is this an example of?