What is one way to test whether and unknown solution is acidic or basic

Assume that the variables x and y are inversely related. if k = 18, what is the value of y for each of the following points? be sure and record your data to be used in the following problem.

How many moles of carbon dioxide will form if 2.5 moles of c3h8 is burned

What is the percent composition of ca(oh)2? 37.7% ca, 53.0% o, and 10.3% h 45.5% ca, 38.2% o, and 16.3% h 54.0% ca, 43.0% o, and 2.7% h 64.7% ca, 27.0% o, and 8.3% h