Why would a block of wood have more friction than a cube

If 10.g of agno3 is available, what volume of 0.25 m agno3 can be prepared

The diagram below shows the different phase transitions that occur in matter. which arrow represents the transition in which dew is formed?

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?