Which of the following statements is true about the bohr model of the atom?
a. an electron orbits in spherical orbits at any distance from the nucleus.
b. an electron orbits in differently shaped orbits at discrete distances from the nucleus.
c. an electron orbits in spherical orbits at discrete distances from the nucleus.
d. an electron orbits in differently shaped orbits at random distances from the nucleus.

Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.

This is the number of complete movements of a wave per second.

Each neuron shown in this figure innervates a group of muscle fibers. what is the term for a group of muscle fibers innervated by a single neuron?