The bright lines visible in the emission spectrum of an element represent? A. the energy released by electrons falling back to a ground state.

B. the colors seen when the element is viewed through a prism at room temperature.

C. the number of protons and neutrons present in the nucleus of the atom.

D. Other:

An implanted pacemaker supplies the heart with 72 pulses per minute, each pulse providing 6.0 v for 0.65 ms. the resistance of the heart muscle between the pacemaker’s electrodes is 550 ω. find (a) the current that flows during a pulse, (b) the energy delivered in one pulse, and (c) the average power supplied by the pacemaker.

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

The freezing and boiling point of a substance changes as the air pressure around it changes. for example, at a lower air pressure (higher altitude) it is easier for water molecules to escape from liquid into the air. in a high altitude city such as denver, colorado compared to a sea-level city such as houston, texas, water