Chemistry-Objective Related Question Answers
151. Most abundant compound on earth's surface?
Water (H20)
152. Most abundant compound in sea water?
Sodium Chloride
153. Second most abundant compound in sea water?
Magnesium Chloride
154. Most chemically reactive element is?
Fluorine
155. Second most chemically reactive element?
Chlorine
156. The lightest and simplest element?
Hydrogen
157. The lightest metal?
Lithium
158. The rarest element in the earth?
Astatine
159. The heaviest element?
Osmium
160. The heaviest gaseous element?
Radon
161. First man made element?
Technetium
162. Most stable element?
Lead
163. The periodic table is divided into 4 main blocks: they are?
S block - elements of group 1 and 2; P block - elements of group 13to 18; D block - elements of group 3 to 12; F block - Lanthanides and Actinides
164. The shortest period of the periodic table?
First period
165. The longest period of the periodic table?
Sixth period
166. Elements with atomic number 57-71 are known as?
Lanthanides (rare earths)
167. Elements with atomic number 89-103 are known as?
Actinides (radio active rare earths)
168. Total number of elements in periodic table?
118
169. The number of naturally occurring elements?
92
170. The first artificial element?
Technetium (Z = 43)
171. Man made elements are known as?
Transuranics
172. Who Classified Elements as Metals and non-metals?
Lavoisier
173. Who Classified Elements as Triads?
Dobereiner
174. Law of octaves was propounded by?
John Newland
175. Who Classified Elements based on atomic weight?
Mendeleev
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