19. Why can lichen grow on bare rock?

Help me plz

The air that we breath is made mostly of which gaseous molecule

Consider the growth of a 20-nm-diameter silicon nanowire onto a silicon wafer. the temperature of the wafer surface is maintained at 2400 k. assume the thermal conductivity of the silicon nanowire is 20 wm-1k-1 and all its surfaces including the tip are subjected to convection heat transfer with the coefficient h = 1×105 wm-2k-1 and t∞ = 8000 k. when the nanowire grows to l = 300 nm, what is the temperature of the nanowire tip (t (x =

An object dropped from cliff falls with a constant acceleration of 10 metre per second square find its speed of two seconds after it was dropped