What's the problem ? Hardness is not the definition of a metal.
You need to expand your thinking. EVERY element is solid, liquid, and gas, over different ranges of temperature ... including all of the metals. There are only TWO elements that are liquid AT ROOM TEMPERATURE, and mercury is one of them. But on a mild day at the south pole, mercury is solid too.
Thank you for posting your question here at brainly. I hope the answer will help you. Feel free to ask more questions.
I think the reaction that represents a balanced, double replacement chemical reaction is B which is <span>Rb2O + Cu(C2H3O2)2 → 2RbC2H3O2 + CuO </span>
The number following the name of the element is the number of subatomic particles inside the nucleus of the atom. This means that it is the mass number of the isotope. The average atomic mass of the element is the sum of the products of the percentage abundance and mass number of the naturally occurring isotopes.
Since, the average atomic mass of the hydrogen is nearest to 1 then, the most abundant isotope should be hydrogen-1.
This noble gas is argon (Ar), because its third energy level is full.
