If you have 250 mL of 0.75 M LINO2.
How many grams of this substance
would you have?

Mass of this substance = 9.928 g

Molarity is a way to express the concentration of the solution

Molarity shows the number of moles of solute in every 1 liter of solute or mmol in each ml of solution

Where

M = Molarity

n = Number of moles of solute

V = Volume of solution

So to find the number of moles can be expressed as

mol of substance -Lithium nitrite - LiNO₂ :

V = 250 ml = 0.25 L

M = 0.75 M

So mass of this substance -  LiNO₂ (MW=52,947 g/mol) :