C
The elements are Lithium and Beryllium— just look at the mass number on the periodic table
Answer:
They are both pretty soft for metals, but magnesium is significantly harder than calcium using this scale . Mg = 2.5, Ca = 1.75. The larger the number, the harder
Explanation:
The atomic radium increases to the left and downwards on the periodic table.
By that logic, Se has the largest radius.
Step (1):
Generation of electrophile: by the action of Lewis acid FeCl₃ on Cl₂ to serve as a source of Cl⁺ (Electrophile)
Step (2):
Addition of electrophile to form carbocation:
addition of electrophile to form C-Cl bond and form carbocation which is stabilized by resonance.
Step (3):
Loss of proton to re-form the aromatic ring by the action of FeCl₄⁻ which removes proton from carbon containing Cl and forming the aromatic ring again