If 15 grams of NaOH is dissolved in 50 grams of
water, what is the pecent by mass of the solution?
Show work please.

An atom of sodium-23 (atomic number = 11) has a positive charge of +1. give this information, how many electrons does it have? how many proteins and neutrons does this atom have

Suppose that a certain fortunate person has a net worth of $71.0 billion ($7.10×1010). if her stock has a good year and gains $3.20 billion (3.20×109) in value, what is her new net worth?

Which of the following is not a characteristic of s waves?