Which part of the eye controls whether or not the pupil dilates or constricts?

iris

cornea

retina

optic nerve

Measure the level of lead in blood

What is the total anion concentration (in meq/l) of a solution that contains 6.0 meq/lna +, 11.0 meq/lca2 +, and 3.0 meq/lli + ?

Which element has the greatest density at STP? a. calcium b. carbon c. chlorine d. copper

You are asked to prepare a ph = 4.00 buffer starting from 1.50 l of 0.0200 m solution of benzoic acid (c6h5cooh and some added sodium benzoate salt (c6h5coona. a find the ph of the benzoic acid solution before adding the salt.

Many organisms in an ecosystem copete with each other for resources. What might different species of trees in a forest ecosystem compete for?

Which of the following is a possible equivalence that can be used in a conversion? A. ten to the negative second power hL over one L B. ten to the negative second power cL over one L C. ten to the first power L over one daL D.

Which process is a chemical change? burning a match boiling water melting ice breaking glass

What form of matter is "vapor"? a. a solid made of a substance that is usually liquid c. a gas made of a substance that is usually solid b. a liquid made of a substance that is usually gas d. a gas made of a substance that is usually liquid

Which of the following atoms releases more energy than oxygen when an electron is added to its valence energy level? Select one: a. helium (He) b. fluorine (F) c. carbon (C) d. nitrogen (N)

End-users of natural gas include (check all that apply) :