Which of the following is true?
1. ear drum contains receptors for hearing
2. cochlea changes shapes to help you focus
3. retina changes light rays into neural impulses
4. lens stimulates the neurons in your olfactory epithelium
5. odor molecules location where sound waves strike

1. ear drum contains receptors for hearing.

Explanation:

Ear drum is an important part of human ear. Its function is to change the sound waves into vibration form and send these vibrations to the inner ear through middle ear i. e. cochlea which is responsible for the hearing and recognizing different sound. Cochlea is a main organ of ear for hearing sounds. If cochlea is damaged, sound can't be hear.

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.

propane is burned to provide the heat in many cooking grills. the chemical reaction for this process is shown in the equation below.

c3h8 + 5o2 ? 3 co2 + 4h2o + energy

what are the products in this chemical reaction?

3co2 + 4h2o + energy