Answer:
Noble gases, atoms which have complete filled outer orbits.
Explanation:
SInce, you have given no options elements like Neon, Helium,etc
According to the Aufbau principle, , electrons orbiting one or more atoms fill the lowest available energy levels before filling higher levels (e.g., 1s before 2s).
The oxidation number of P in Mg3P2 is 3. When writing ionic compounds, you swap the oxidation numbers and add them as the subscript.
Explanation:
The given data is as follows.
Refractive index of mixture = 1.456
Refractive index of hexane = 1.375
Refractive index of toulene = 1.497
Let mole fraction of hexane =
and, mole fraction of toulene =
Also, 
or, 
Hence, calculate the mole fraction of hexane as follows.
refractive index mixture= mole fraction hexane × ref index hexane + mole fraction toluene × ref index toluene.
1.456 = 
1.456 = 
0.081 = 
= 
= 0.66
Since, 
= 1 - 0.66
= 0.34
Thus, we can conclude that mole fraction of hexane in your sample is 0.34.
<span>(K⁺¹)2Cr(O⁻²)4
+1*2 +x-2*4=0
2+x-8=0
x=6
Oxidation number of Cr is +6.</span>