Answer:
Partial pressure of He = 73 kPa
Explanation:
Given:
Total pressure = 125 kPa
Partial pressure of Ne = 31 kPa
Partial pressure of Kr = 21 kPa
Find:
Partial pressure of He
Computation:
Total pressure = Partial pressure of Ne + Partial pressure of Kr + Partial pressure of He
125 kPa = 31 kPa + 21 kPa + Partial pressure of He
Partial pressure of He = 73 kPa
C = 12 g
O = 16 g
H = 1 g
<h3>Further explanation
</h3>
Conservation of mass stated that
<em>In a closed system, the masses before and after the reaction are the same
</em>
we can calculate the mass of each atom in the compound :
O in O₂ :
mass O₂ = 32
mass O = 32 : 2 = 16 g
H in H₂O
mass H₂O = 18
mass 2.H + mass O = 18
mass 2.H + 16 = 18
mass 2.H=2
mass H = 1 g
C in CH₄
mass CH₄ = 16
mass C + mass 4.H = 16
mass C + 4.1=16
mass C = 12 g
or we can use formula :
Mass of a single C :

Rutherford's gold foil experiment proved that there was a small, dense, positively charged nucleus at the center, which contained most of the mass of the atom. Which contained electrons orbiting the nucleus.
s - orbitals have a spherical symmetry and the probability of finding an electron in an s orbital is equal for equal distance in x, y or z direction. i mean the probability of lets say an electron found at a distance 10 units from nuclues, its value will be same for x, y and z when u go 10 units distnace from nucleus in these directions. then the value at 5 units would be some value which also would be same for x,y and z.
Easier explanation is that if u place a ball, can u tell towards which axis it is oriented? no, its equally in all directions. So, non- directional.
However, if you have p- orbitals like dumb bells, a dumb bell can be oriented in three different directions, either x or y or z. see the pics.