What is the result of multiplying 2.5 by 3.51 in the correct amount of significant figures

A+b→2c when the reaction begins, the researcher records that the rate of reaction is such that 1 mole of a is consumed per minute. after making changes to the reaction, the researcher notes that 2 moles of a are consumed per minute. what change could the researcher have made to effect this change?

What is driving behind plate tectonics (plate movment)? a) gravity only b) inertia c) convection and gravity d) the sun theres no option for science so i picked chemistry. plz

What are the spectator ions in 2h+ + so42- + ca2+ + 2r → caso4 + 2h+ + 21?