How many moles are 21.67 L of NH4CI?

How will the emission of an alpha particle affect the atomic number of an atom

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?

The student repeated the experiment using a higher concentration of acid. the same volume of acid and the same mass of magnesium ribbon were used. what volume of hydrogen gas would have been produced after 60 seconds?