Le diamant est un cristal constitué uniquement
d'atomes de carbone. On
considère que ces atomes sont
tous des atomes de carbone
12 (A = 12 nucléons). Il faut
en moyenne traiter 20 tonnes
de minerai pour extraire 1,0 g
de diamant, soit 5,0 carats.
Le diamant coûte très cher:
un diamant de 1,1 carat peut être vendu 15 000 €.
• Combien coûte un «atome de diamant»?
Donnée
mnucléon = 1,67 x 10-22 kg.

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)

Word equation for k(s) +h2o(l) yield koh (aq) + h2