The answer is:
Oxygen
Carbon
argon
boron (metalloid)
The explanation:
-metal : any of various opaque, fusible, ductile, and typically lustrous substances that are good conductors of electricity and heat, form cations by loss of electrons, and yield basic oxides and hydroxides; especially: one that is a chemical element as distinguished from an alloy
-nonmetal : a chemical element (as Oxygen, carbon, or nitrogen) that lacks the characteristics of a metal and that is able to form anions, acidic oxides, acids, and stable compounds with hydrogen
-Non-metals are the elements in groups 14-16 of the periodic table. ... The non-metals exist in two of the three states of matter at room temperature: gases (such as oxygen) and solids (such as carbon). The non-metals have no metallic luster and do not reflect light. They have oxidation numbers of ±4, -3, and -2
1-Gallium is a chemical element with symbol Ga and atomic number 31. It is in group 13 of the periodic table, and thus has similarities to the other metals of the group, aluminium, indium, and thallium. ... Since its discovery in 1875, gallium has been used to make alloys
2-Yttrium is a chemical element with symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element"
3-Argon is a nonmetal. It is a noble gas, located in group 18 (far right column on the periodic table). ... Elements to the left of this line are metals, while elements to the right of this line are nonmetals
4-Polonium has a position in the periodic table that could make it a metal, a metalloid or a nonmetal. It is classed as a metal as its electrical conductivity decreases as its temperature rises
5-Boron is classified as a metalloid, it has properties of both metals and nonmetals. ... I'd say Boron is a non metallic element and the only non-metal of the group 13 of the periodic table the elements. Boron is electron-deficient, possessing a vacant p-orbital.
6-Carbon is a solid non-metal element. Pure carbon can exist in two very different forms - diamond and graphite. The table shows some differences between them. Diamond is the hardest natural substance on Earth, but it is also very brittle and will shatter if hit with a hammer.
7- Oxygen is non-metals, It is one of the elements in groups 14-16 of the periodic table. ... It exists in two of the three states of matter at room temperature.
