Which elements are solid and gray?

Answer 1

Under what conditions?

Most metals at ordinary conditions (those you might find in, say, your living room) are solid and "gray" (if your definition of "gray" includes silver). A lot of the semi-metals/metalloids are also. Iodine isn't a metal or a semi-metal, but it's solid and sort of gray at those temperatures and pressures anyway.

The metals that aren't solid and gray at STP:

Mercury (liquid and silvery)

gold (solid and ... well ... gold)

copper (solid and reddish-orange)

caesium (solid, but melts just above room temperature, and it's a very pale yellow color)

bismuth (solid with a very faint pinkish tinge)

Also, a lot of metals tarnish with exposure to air and form a thin (or not so thin) layer of the metal oxide (or sulfide, sometimes). This layer may make the metal appear to be some color other than the pure element (for example, bismuth forms a surface layer of oxide, and depending on the thickness it can be just about any color from deep pink to blue).