How many mililiters of a solution of 3% w/v, 4% w/v and 7% w/v should be used to prepare 4 pint of a 5 % w/v solution.

1. How many milliliters of a 1:20 w/v solution of copper sulfate should be used to prepare 1 L of a 0.50% w/v solution?

2. How many grams of lidocaine should be added to a 2 % lidocaine ointment to prepare 1000 g of 5% of lidocaine ointment? (Mixing pure lidocaine and 2% lidocaine ointment)

18. how many milliliters of 6.44 M perchloric acid solution should be used to prepare 4.50 L of 0.600 M HClO4? mL