Effect Of Temperature On The Mobility And Conductivity Of Electrons And Holes

What is the effect of temperature on the conductivity of metals and semi-metals ?

The effect of temperature increase on conduction as -

The contribution in the total current flowing through a semiconductor due to electrons and holes are 3/ 5 and 2/ 5 respectively. If the drift velocity of electrons is 2 times that of holes at this temperature, then the ratio of concentration of electrons and holes is

The contribution in the total current flowing through a semiconductor due to electrons and holes are 3/4 and 1/4 respectively. If the drift velocity of electrons is 5/2 times that of holes at this temperature, then the ratio of concentration of electrons and holes is

What is the effect of temperature on thermal conductivity of substances?