A 1.53 mol sample of helium gas was placed in a balloon. Adding 7.00 mol of helium gas to the balloon increased its volume to 12.5 L. Assume that temperature and pressure remained constant. What was the initial volume of the balloon in liters?

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Dona wrote the characteristics of two types of galaxies as shown below: type a: has a large flattened core type b: does not have a regular shape which statement is correct? type a is an irregular galaxy and type b is a lens galaxy. type a is a lens galaxy and type b is an irregular galaxy. type a is a spiral galaxy and type b is an elliptical galaxy. type a is an elliptical galaxy and type b is a spiral galaxy.