Pumice is a type of rock formed when gas bubbles are trapped inside of cooling lava. pumice is most often formed when volcanoes erupt violently. what type of rock is pumice? a) extrusive igneous b) intrusive igneous eliminate c) contact metamorphic d) foliated metamorphic

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.