A doctor uses an instrument(s) that emits light and allows the doctor to view the inside of a patient’s intestine. What is the doctor most likely using?

a telescope
a microscope
laser beams
fiber optics

The answer for #3 is c but i don't know why

A50.0 ml sample of gas at 20.0 atm of pressure is compressed to 40.0 atm of pressure at constant temperature. what is the new volume? 0.0100 ml 0.325 ml 25.0 ml 100. ml

Given the following information: mass of proton = 1.00728 amu mass of neutron = 1.00866 amu mass of electron = 5.486 × 10^-4 amu speed of light = 2.9979 × 10^8 m/s calculate the nuclear binding energy (absolute value) of 3li^6. which has an atomic mass of 6.015126 amu. j/mol.