What is the color of bromcresol green indicator in a solution with a pH value of 2.0? (1) blue (2) green (3) red (4) yellow Answer: Choice 4 Solution: An indicator allows us to figure out the pH range of the solution and whether it is acidic or basic. To do this problem, we need to look at Table M of the Regent Reference Table, Common Acid–Base Indicators. According to the table, bromcresol green, has a pH range for color change of 3.8-5.4 and the color change is yellow to bl

Which notations represent atoms that have the same number of protons but a different number of neutrons? (1) H-3 and He-3 (2) S-32 and S-32 (3) Cl-35 and Cl-37 (4) Ga-70 and Ge-73 Answer and Explanation: Choice 3 is the correct answer choice Atoms of the same element that have the same number of protons but a different number of neutrons are called isotopes. Whenever we see an element symbol followed by a dash and a number, that number represents the mass of the element. Choi

Which formula represents an asymmetrical molecule? (1) CH4 (2) CO2 (3) N2 (4) NH3 An assymetrical molecule is a molecule whose charge is distributed unevenly. A polar molecule is an asymmetrical molecule. How can we figure out if the molecule is polar? First we need to draw the Lewis dot structures for the molecules. For a molecule to be non polar, we need the central atom to be surrounded by identical elements and have no lone electron pairs. For example, CH4 is non polar be

What is the number of moles of KF in a 29gram sample of the compound? (1) 1.0 mol (2) 2.0 mol (3) 0.50 mol (4) 5.0 mol Answer and Explanation: To find the number of moles, you can look at the Reference Table, Table T and find the formula for moles. Number of moles = given mass/ gram-formula mass Therefore let's use first fine the gram formula mass by looking at the periodic table. K has a mass of 39g/mol and F is 18.998 g/mol. Therefore mass of KF = 39+18.998 = 57.998g/mol Nu

A sample of gas is in a rigid cylinder with a movable piston. The pressure of the gas is kept constant. If the Kelvin temperature of the gas is doubled, the volume of the gas is (1) halved (2) doubled (3) tripled (4) unchanged Answer and Explanation: Looking in the back of the Chemistry reference table, we can see the combined gas law that gives us the relationship between gas, volume, and temperature. The formula is P1V1/T1 = P2V2/T2. Since the pressure is constant, we can

Which atom in the ground state has a stable electron configuration? (1) carbon (2) magnesium (3) neon (4) oxygen Answer and explanation: Electron configuration is the distribution of electrons in an atom. In order for the electron configuration to be stable, an atom (o ther than Hydrogen and Helium) must have a full outer octet, or 8 electrons in it's outermost shell. Hydrogen and Helium only need 2 electrons to be stable. Therefore, we need to search for atoms with a full o

A magnesium atom that loses two electrons becomes a (1) positive ion with a smaller radius (2) negative ion with a smaller radius (3) positive ion with a larger radius (4) negative ion with a larger radius Answer and Explanation: To answer this question we first must think what charge an electron has. Electrons are negatively charged. Therefore, losing two electrons will make magnesium a positively charged ion. You can also see this in the periodic table by looking at charge

What is the oxidation number of manganese in KMnO4? (1) +7 (2) +2 (3) +3 (4) +4 Answer and Explanation: We can figure out the oxidation number of Manganese by making a simple equation. First, we need to see what are the oxidation numbers of all of the other elements. We can find these numbers on the periodic table. We can see that K has +1 number while oxygen is -2. Therefore, we can now make our equation. All the oxidation numbers must add up to 0, since the molecule is neut

Proteins, starch, and DNA are similar in that they are all (1) organic compounds (2) parts of genes (3) made of amino acids (4) made of simple sugars Answer and Explanation: Proteins, starch and DNA are all important molecules in our body. What do they have in common? Well let's take a look at the answer choices and figure out. Only starch is made of simple sugars, while proteins are made of amino acids, and DNA contain genes that code our genetic information. Therefore, choi

A solid sample of a compound and a liquid sample of the same compound are each tested for electrical conductivity. Which test conclusion indicates that the compound is ionic? (1) Both the solid and the liquid are good conductors. (2) Both the solid and the liquid are poor conductors. (3) The solid is a good conductor, and the liquid is a poor conductor. (4) The solid is a poor conductor, and the liquid is a good conductor. Answer and Explanation: Ionic compounds have uniq