Based on its position in the periodic table, which of the following elements is most reactive, helium, carbon, argon, or fluorine

Periodic table is a table that arranges elements based on physical and chemical properties into groups and periods. Non metals reacts by gaining electrons, the ease of gaining electrons determines the reactivity of a non metal. Argon and helium belong to group eight of the periodic table therefore are unreactive (inert), carbon belongs in group thus reacts by gaining 4 electrons while fluorine is a group 7 element and reacts by gaining 1 electron. Therefore, the answer is fluorine,since it requires to gain only one electron.

Initial velocity,  u = 4.9 m/sfinal velocity = v m/sinitial height,  h₁ =  245 m    final height, h₂ = 0a = -9.8  m/s²time taken = t secondss = ut + 0.5at²⇒  (h₂-h₁) = ut + 0.5at²⇒  0-245 = 4.9t + 0.5×(-9.8)×t²⇒ -245 = 4.9t - 4.9t²⇒ 4.9t² -4.9t -245 =0solving it, we get   t = 7.59sv  = u +  at = 4.9 -9.8×7.59 = 4.9 - 74.38 = -69.48 m/svelocity is  69.48 m/s downward