Bond energy needed to break or create bonds is measured in units called A horsepower
B. calories
C. kilojoules
D. newtons

(Edit)
Correct Answer is "C"

C. kilojoules

Explanation:

The bond energy needed to break or create bonds is measured in units called kilojoules.

Bond energy is a form of enthalpy change of a reaction or physical change. The bond energy is the heat content of a covalent bond formed from its constituent elements in the gas phase.

The bond energy is the same in value as the bond dissociation energy and its unit is given in kilojoules.

the grams   of   barium that   are in   2.3 x 10^23   atoms of barium   is   52.4 g (answer c)

    calculation

mass = moles   of ba   x molar   mass of ba

  molar mass of ba from periodic table=   137.3 g/mol

  use the   avogadro's law   constant   to   calculate the moles of barium

  that   is     1 mole =   6.02   x 10^23 atoms

                    ? moles = 2.3 x 10^23   atoms

by cross   multiplication

=(1 mole   x 2.3x 10^23 atoms)   / 6.02   x10^23 atoms)=   0.382   moles

mass   is therefore = 137.3   g/mol x 0.382 mol = 52.4 ( answer c)

explanation: