Four waves are produced when a harp is strummed at four different times. Wave 1
A thick, middle
string is strummed
at 70 dB
Wave 2
A thick, middle
string is strummed
at 26 dB
Wave 3
Wave 4
The long, thin The short, thin
string on one end string on one end
of the harp is of the harp is
strummed at 20 dB. strummed at 56 dB.
Which wave will produce the highest pitch?
Wave 1
Wave 2
o Wave 3
Wave 4

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.

c.

explanation:

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.