I need help answering that middle question

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Explanation:

californium is a synthetic radioactive element found on the bottom row of the periodic table, along with other actinides.

It was first discovered in 1950 at the University of California Radiation Laboratory in Berkeley by bombarding curium with alpha particles (helium nuclei). Pure californium metal has a silvery-white appearance and is soft enough to be easily cut with razor blade.

In initial experiments with californium in its concentrated form began in 1958.

Since then, 20 isotopes of californium have been characterize, with mass numbers ranging from 237 to 256. One of these isotopes is californium-252, which was first isolated from a neutron-irradiated sample of plutonium-239. As an exclusively synthetically made element (it cannot be found in nature),

californium-252 is very rare an is produced via neutron bombardment in high flux isotope reactor or particle accelerators.

On this,page we walk through some of the properties  and uses of his unique isotope and provide additional resources for your reference.

Hope this helps! :)

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).