Is air an element, compound, homogeneous mixture, or a heterogeneous mixture?

When the chemicals iron sulfide (fes) and hydrochloric acid (hcl) are combined, bubbles appear from the mixture. 1. does the appearance of bubbles indicate a physical or chemical change? 2. why do the bubbles indicate this change? 3. what property is this?

Vi limitens. vastery test select the correct answer. which statement explains why large atoms are more reactive than small atoms? a. large atoms have valence electrons farther from the nucleus and lose them more readily. b. large atoms have greater ionization energy, which they can utilize during a reaction. c. large atoms have a greater number of electrons that they can lose during a reaction. d. large atoms have more energy levels, so they have more energy to pass on in a reaction. reset next

How many moles are in 1.26*10^24 particles in significant figures