When group 2a element from ion they

a. lose two proton
b. gain two proton
c. lose two electron
d. gain two electron

Well, knowing that group 2A elements are metals, and metals lose electrons to gain a full electron shell, we can eliminate B and D. Knowing that these are 2 electrons, that the group 2A element provides to another atom, to form an ion.

The solution is C. Lose 2 electrons.

When the prong of a tuning fork next to the tube moves toward the tube, a compression enters the tube. When the prong swings away, in the opposite direction, a rarefaction follows the compression. As the source vibrates, a series of compressions and rarefactions is produced.