You volunteer for chalkboard cleaning duty and you get to work with the erasers. as you rub the dust off of the chalkboard, white chalk dust enters the air and makes you cough. as you clean the chalkboard with the eraser, are you causing a physical change or a chemical change ? explain your answer .

A physical change

Explanation:

A physical state is one that alters the physical properties of matter. In most cases physical changes are easily reversible. The physical properties of matter shows everything about a matter when no change is occuring to it.

When writing on a chalkboard, the state of matter is barely changing from a solid mass of chalk to a powdered form which can easily mark the board.

No change is occuring to the board besides the colour marking it which can easily be erased.

Physical changes can easily be reversed using seperation techniques, in this case, merely wiping the board.

To show that no chemical change has occur, no new kind of compound is formed when marking the board. We can easily collect the powdered chalk back.

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).