An unknown metal displaces aluminum (Al) from solution but does not displace sodium (Na). Using the activity series, determine the unknown metal. A.
calcium (Ca)

B.
zinc (Zn)

C.
manganese (Mn)

D.
magnesium (Mg)

Magnesium or calcium as they are both more reactive than aluminium and less reactive than sodium

magnesium (Mg) Please dont be like the dummy above and say two answer's THATS NOT AN ANSWER THATS A GUESS but here you go :)

Also not being rude but report incorrect answer's I'm assuming like myself you guy's are paying so you don't have to stress over school so please if you see a multi answer that makes no sense like the guy above please report it. have a wonderful day and sorry about the long message.

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).