7. which of the following has to happen before the eardrum begins to vibrate with the same frequency as the source of the sound waves?
a. vibrations have to be transmitted to the fibers of the auditory nerve.
b. impulses have to be sent to the brain through the auditory nerve.
c. the brain has to interpret the direction from which the sounds are being delivered.
d. the outer ear has to collect the sound waves and lead them to the middle ear.

Answer : Option D) The outer ear has to collect the sound waves and lead them to the middle ear.

Explanation : Hearing is dependent on a series of complex steps that change vibrations of sound waves in the air into electrical signals. At first the vibrations of sound waves gets collected by the outer ear and from there sound waves travel through a narrow passageway called the ear canal, which leads to the eardrum. The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear. The auditory nerve then carries these signals to the brain.

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g

i would say b

explanation:

but i think i would need more information than that