I think the mass the mass was less than the original because a gas was released into the atmosphere. The mass in a chemical reaction is constant in a closed system according to conservation of mass law. However, if a chemical reaction is completed in an open system, mas changes may occur. In our case i think the change in mass was due to the release of hydrogen gas from the reaction to the atmosphere.
Agree with the statement buddy
Precipitation reactions are those reactions in which two aqueous solutions, when mixed, react to form a solid. The solid thus formed is known as a precipitate. Thus, a precipitate is an insoluble solid (recall that an insoluble substance is one which does not dissolve). ... We have defined precipitates as insoluble solid
With newly discovered materials, nothing is yet know about them. Scientists don't know how to conduct physical/chemical experiments without damaging the element. Lethal substances or corrosive materials can be set off from combustion or decomposition. It would be difficult to determine the properties because no one knows what the element is made of. Chemical properties are often characterized by <span>reactivity with other chemicals, such as toxicity, coordination number, flammability, enthalpy of formation, the heat of combustion, and <span>oxidation states. It is difficult to measure those things when you have no idea what an element may be giving off. </span></span>