a charged particle in an accelerated motion produces em radiation.
in an atom the electrons have accelerated motion. does it means that all electrons in atoms produce em

Yes. all the accelerating charged electron particles produces the Electromagnetic wave.  

Explanation:

Magnetic fields are produced during the movement of the charged particle. the magnetic field produced, will exert some force in the moving charges. The electric field as well as the magnetic field travelling in the empty space with respect of speed of light are the electromagnetic wave. Moving electron will always produce the magnetic field and thus the electrons motion are constant,but when the acceleration starts the electromagnetic waves are being radiated.

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).

they vary. it used to be meat, grain, bread, candy, beverages, donuts, and fruits/vegetables. now they added exercise in.