I need help boys-girls

What volume of a 2.00 m stock solution of naoh is needed to prepare 150. ml of 0.40 m solution?

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.

To calculate percent by mass, use the equation below: calculate the percent by mass of each element. %n = % %h = % %o = %