<u>Answer:</u> The mass of methylene blue that must be weighed is 
<u>Explanation:</u>
To calculate the mass of solute, we use the equation used to calculate the molarity of solution:

We are given:
Molarity of solution = 
Molar mass of methylene blue = 319.85 g/mol
Volume of solution = 100.0 mL
Putting values in above equation, we get:

Hence, the mass of methylene blue that must be weighed is 
<span>The answer is A. Gases are spread throughout the air and not packed tightly together. therefore the molecules move quickly and are least densely packaged. They have the highest energy because they also have the highest molecular motion. </span>
If the core were to cool completely, the planet would grow cold and dead. It also would get a little dark: Power utilities pull radiant heat from Earth's crust and use it to heat water, the steam from which powers turbines to create electricity.Cooling also could cost us the magnetic shield around the planet created by heat from the core. This shield protects Earth from cosmic radiation. The shield is created by a convection process caused by constantly moving iron. Like the planet itself, Earth's core is constantly spinning. Some scientists think it's moving even faster than the rest of the planet. The friction converts kinetic energy into electrical and magnetic energy that forms the field, which deflects harmful, charged particles emanating from the sun toward the north and south poles. Your welcome :)
The answer is 20 because in an atom no of protons equal no of electrons