The atomic number of Sodium(Na) =11.
The correct electronic configuration of sodium is 2,8,1.
So, The correct option is (d) 2,8,1.
In Fig. 9.26, A, B, C and D are four points on a circle. AC and BD intersect at a point E such that ∠ BEC = 130° and ∠ ECD = 20°. Find ∠ BAC.