A gas at 400 K and 10.0 L expands to 20.0 L. What is its new temperature in Kelvin?

Which factor is likely to impact the possible number of compounds ?

Awhite powder is added to a solution. the images show observations made before the powder is added, just after the powder has been added, and a little while later. (the liquid in the small beaker is phenol red solution.) what evidence shows that a chemical change has taken place?

What volume of 0.500 mol/l hydrochloric acid, hci (aq) is required to react completely with 1.00 g of aluminum hydroxide, ai(oh)3 (s)?