Question

which of the following is not a metal​

Answer 1

Silicon is neither metal nor non-metal. It is the one which falls between both known as metalloid. Metalloid have both property of metal and non-metal.

Answer 2

Non-metals are the elements which form negative ions by accepting or gaining electrons. Non-metals usually have 4, 5, 6 or 7 electrons in their outermost shell. Non-metals are those which lack all the metallic attributes. They are good insulators of heat and electricity. They are mostly gases and sometimes liquid.  example hydrogen carbon and sulphur