When I was a boy, Uncle Wilbur let me watch as he analyzed the iron content of runoff

Introductory Chemistry 5
Classify each substance as a pure substance or a mixture. If it is a pure substance, classify it as an element or a compound. If it is a mixture, classify it as homogeneous or heterogeneous. (a) urine (b) pure water (c) SnickersTM bar (d) soil

Introductory Chemistry 5
For each compound, list the correct formula and calculate the formula mass. (a) tin(IV) sulfate (b) nitrous acid (c) sodium bicarbonate (d) phosphorus pentafluoride

Introduction to Probability, 2
A motorist goes through 4 lights, each of which is found to be red with probability 1/2 . The waiting times at each light are modeled as independent normal random variables with mean 1 minute and standard deviation 1/2 minute. Let X be the total waiting time at the red lights. (a) Use the total proba

Campbell Biology 10
SCIENTIFIC INQUIRY Female silkworm moths (Bombyx mori) attract males by emitting chemical signals that spread through the air. A male hundreds of meters away can detect these molecules and fly toward their source. The sensory organs responsible for this behavior are the comblike antennae visible in t

Chemistry for today : general, organic, and biochemistry 9
Refer to the group numbers of the periodic table and draw Lewis structures for atoms of the following: a. potassium b. barium c. aluminum d. bromine

Biology: The Dynamic Science 5
About 200 years ago, Jan Baptista van Helmont tried to determine the source of raw materials for plant growth. To do so, he planted a young tree weighing 5 pounds in a barrel filled with 200 pounds of soil. He watered the tree regularly. After 5 years, he again weighed the tree and the soil. At the s

Biochemistry 9
What is propeller twist?