Which of the following combinations will produce a 0.4 m nacl solution?

a) mixing 500 ml of 0.4 m naoh with 500 ml of 0.4 m hcl
b) mixing 300 ml of 1.2 m naoh with 600 ml of 0.6 m hcl
c) mixing 500 ml of 0.4 m nacl solution with 500 ml water
d) diluting 400 ml of 0.6 m nacl with water to a final volume of 1.0 l

Option C: Mixing 500 mL of 0.4 M NaCl solution with 500 mL water

Explanation:

0.4M is [NaCl]

Molar concentration which means moles of solute in 1L.

How many moles, do we have in our volume of 500 mL

Molarity . volume = mole

0.4 mol/L . 0.5L = 0.2 mole

(remember convert mL to L)

This 0.2 mole of NaCl that were in 500 mL, are also in 500 mL of water, so In 1L of water, I have the double of mole, so 0.4M

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).

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).