A ring of radius 2.50 cm has a uniform linear charge density of 15.0 nC/m. It is observed that when a point charge Q is placed at the center of the ring, the electric field at a point at the central axis of the ring at a distance of 12.0 cm from its center is zero. What is the value of Q?

its c its is a mixture of gases

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.

wavelength divides in half and speed stays the same.