Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles. We do as follows:
10 mol NH3 ( 6.022 x 10^23 molecules / 1 mol ) = 6.022x10^24 molecules NH3
BaS.
because needs 2 electrons and S have 2 extra electrons
The units are nm (nano-meter), km (kilo-meter), pm (pico-meter), dm (decimeter), mm (millimeter), m (meter), cm (centimeter), hm (hectometer) and gm (gigameter). Now we can express each of these units in terms of m.
1 nm =
, 1 Km =
1 pm =
, 1 dm = 0.1 m, 1 mm = 0.001 m, 1 cm = 0.01 m, 1 hm = 100 m, 1 gm =
. Thus the decreasing unit will be
gm>km>hm>m>dm>cm>mm>nm>pm
A 3 sig figs
B 6 sig figs
C 2 sig figs
D 5 sig figs
C, A, D, B