Explain why hydrogen gas is given off when a reactive metal undergoes a single-displacement reaction with water.

Idon’t understand this page, can someone ?

Ageochemist examines a piece of metal that he found in the soil. he performs tests to identify the metal from its density, electrical conductivity, and melting point. which statement best describes his investigation? a. he is determining physical properties that are sufficient to identify the metal.b. he is determining chemical properties that are sufficient to identify the metal.c. he is determining physical properties that are insufficient to identify the metal.d. he is determining chemical properties that are insufficient to identify the metal.

Can someone me with 6 to 10 plz this is for masteries test.