Is grinding the coal to obtain the active coal a physical or chemical reaction​

Great amounts of electromagnetic energy from our sun and other bodies in space travel through space. which is a logical conclusion about these electromagnetic waves? their energy must be very their frequency must be very low these waves can travel without a medium they only travel through a vacuum of space

What is the main reason why some developing countries fear the increase the free trade policies around the world?

Δu of , in kj/kg, as it isto k, (a)as a of , (b) at , (c) at .