The fourth (last) one in 2-8-8-2.
The moon should be between the sun and Earth
B
Meniscusity the convex or concave upper surface of a column liquid, the curvature of which is caused by surface tension
2.) Average atomic mass =Σ (abundance x molar mass) /100
= (12.64 x 302.04 + 18.23 x 304.12 + 69.13 x 305.03) /100
=304.486 u(Dalton) . This is avg atomic mass.