Which of these elements have the same number of valence electrons? A. Hydrogen(H) and helium (He)
B. Sodium (Na) and potassium (K)
C. Carbon (C) and oxygen (O)
D. Boron (B) and beryllium (Be)​

A5 foot by 5 foot box culvert is buried 6 feet beneath the surface of the ground. a crosssection of this very long culvert (into and out of the page) is illustrated below. assume that the soil in which the culvert is buried has the following properties: jt = 120 pcf, w = 12%, ko = 0.50, ka = 0.33, and kp = 3.00. calculate the total horizontal force per unit length of culvert (fh) felt on one of the vertical faces of the culvert.