What is the % by mass of Na2SO4 in a solution that contains 65.2 g Na2SO4 dissolved in 350 mL H2O?

What are the percent by mass of copper in penny lab

Scientists often have to deal with numbers that are either very large or very small. for example, the radius of the sun is approximately 696,000 kilometers, while bacterial cells are as small as 1.9 × 10-4 millimeters. express each number in an alternate form.

Element j is 1s 2s 2p 3s . (i) how many unpaired electrons does j have? (ii) is j a good oxidizing agent or a reducing agent? (iii) state reason for the answer.