What is the ph of a 0.0025m hci solution?

Avariable that is not being directly tested during an experiment should be changed varied experimented controlled

Which substance has non polar covalent bonds

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?