26) C

Xenon hexafluoride has 1 xenon atom and 6 fluorine atoms. (The prefix hexa- means six)

Fluorine is diatomic gas. In order to receive 6 fluorine atoms, we need to use three fluorine gas molecules (3F2)

Xenon is a noble gas so it is present as an atom only.

We can write down the equation too.
Xe + 3F ->   XeF6     ∆H = -330 kJ/mol

Number of F – F bonds broken = 3
Energy = 158 x 3 = 474 kJ/mol

There are 6 Xe – F bonds.
Let energy of 1 Xe – F bond = M (any letter)
474 + 330 = 6M
6M = 804
M = 134 kJ/mol