A researcher is trying to identify whether household substances are basic. Which approach would BEST help the researcher investigate whether substances are basic?
A. Observe each substance and record its color.
o B. Measure the temperature of each substance.
C. Test each substance with red litmus paper.
OD. Mix each substance with a weak base and record the results.

Me, prove a quadrilateral with vertices g(1,-1), h(5,1), i(4,3) and j(0,1) is a rectangle using the parallelogram method and a rectangle method.

1- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis.2- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in the first question?

Consider the set of all four-digit positive integers less than 2000 whose digits have a sum of 24. what is the median of this set of integers?