is it possible to gain or lose mass or energy after a chemical reaction has occurred in a closed system?

Based on the equation and the information in the table, what is the enthalpy of the reaction?

(1.6 × 10-19)(5.0 × 106) = c × 10d identify the missing numbers below to show the result of multiplying the numbers.

Which of the following shapes would represent a molecule with two bonded atoms and 3 lone pairs on only one of them , trigonal planar , bent , trigonal pyramidal , linear