What is the number of moles of solute in 250ml of a 0.4m solution?

There are 0.1 moles of solute in 250 mL of 0.4 M solution.

Explanation:

First, recognize that the molar concentration tells you how many moles of the solute are present in one liter of solution. In a 0.4 M solution, there are 0.4 moles of solute in every liter of solution. You can determine the number of moles of solute in 250 mL of the solution using dimensional analysis.

250mL⋅

1L/1000mL⋅

0.4mol1L

Units of liters and milliliters cancel, leaving you with a final answer in units of moles, at 0.1 mol.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.