What is the mass number of an atom that contains 19 protons, 19 electrons, and 20 neutrons?

If 3.00 g of titanium metal is reacted with 6.00 g of chlorine gas, cl2, to form 7.7 g of titanium (iv) chloride in a combination reaction, what is the percent yield of the product?

Which of the dna typing techniques do you think you would choose if you had to analyze a dna sample? why?

What are the 4 phases of matter in order of increasing engery content?