12, if the decimal is over five, round up. If it's not, round down. Not sure what you mean by significant figures.
Ok what’s the question sir
Answer:
metal calcium or (Ca).
Explanation:
For example, the metal calcium (Ca) and the nonmetal chlorine (Cl) form the ionic compound calcium chloride (CaCl2). In this compound, there are two negative chloride ions for each positive calcium ion
. The energy of shells in a hydrogen atom is calculated by the formula E = -Eo/n^2 where n is any integer, and Eo = 2.179X10^-18 J. So, the energy of a ground state electron in hydrogen is:
E = -2.179X10^-18 J / 1^2 = -2.179X10^-21 kJ
Consequently, to ionize this electron would require the input of 2.179X10^-21 kJ
2. The wavelength of a photon with this energy would be:
Energy = hc/wavelength
wavelength = hc/energy
wavelength = 6.626X10^-34 Js (2.998X10^8 m/s) / 2.179X10^-18 J = 9.116X10^-8 m
Converting to nanometers gives: 91.16 nm
3. Repeat the calculation in 1, but using n=5.
4. Repeat the calculation in 2 using the energy calculated in 3.
Answer:
There are twice the molar quantity of nitrogen atoms in nitrous oxide, i.e.
1×10−2⋅mol
Moles of nitrous oxide
=
0.217
⋅
g
44.013
⋅
g
⋅
m
o
l
−
1
=
5
×
10
−
3
⋅
m
o
l
.
Given the composition of
N
2
O
, there are this
2
×
5
×
10
−
3
⋅
m
o
l
of nitrogen atoms.
