Please help me this is my last question

The enthalpy of formation of water is -285.8 kj/mol. what can be inferred from this statement?

Match the following items. 1. high-intensity bundle of energy being emitted from some decaying nuclei gamma ray 2. particle radiating from the nucleus of some atoms beta particle 3. negative particle identical to an electron but radiating from a decaying nucleus alpha particle

Acrystal that absorvd water from air is (blank)a. aqueousb. homogenousc. hygroscopicd. efflorescent