17.observe the given figure carefully-
the given figures show the path of light through lenses of two different types, represented by rectangular boxes a and b.
what is the nature of lenses a and b?

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.