If a volcano has viscous lava, does it have a low or high silica content?

Which of the following is an example of an outdated theory based on the consensus of the scientific community ? a. big bangb. geocentric solar systemc. heliocentric theoryd. plate tectonics answer : geocentric solar system

The meseta in spain is a a. navigable river b. castle c. coastal plain d.plateau

In russia which of these challenges affects the transportation of both petroleum products and other goods?