Which of the following has the highest atomic size ? a beryllium b strontium c barium d radium

D. Radium

Explanation: The atomic size of an atom increases when it moves down in a group. The number of energy levels increases due to the increase number of electrons. This contributes to the increase in atomic size since energy orbitals becomes farther from the nucleus.

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.

there are no contact forces mentioned on the list of choices that you've provided.