Which substance has a high melting point and conducts electricity in the liquid phase

How many grams of naoh are needed to make 0.250 liter of a 0.500 m solution of naoh? 0.125 g 5.00 g 2.00 g

You are making a solution of calcium chloride dissolved in water. you add solid, stir, and it dissolves. you add just a spatula tip full, stir, and the solid does not dissolve. how could you describe the solutions before and after adding the spatula tip amount

Sum of brother and sisters age is 26. four times the brothers age is subtracted from three times the sisters age, the difference is 8. what are the ages of the brother and sister?