Respuesta :

 Yes, except the answer should only be to 1 or 2 significant figures, because you are only given the voltage to 1 significant figure. 

E = QV = 1.6x10⁻¹⁹ x 9 
= 1.4x10⁻¹⁸ J


Answer

2.3333 Coulombs


Explanation

The average work done to move by a  battery  is given by:

∴ Work done = QV

Where Q is the number of charge and V is the voltage from the cells.

21 = 9Q

21 = 9Q

Q = 21/9

  = 2.3333 Coulombs