November 11, 2019

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 co...

October 8, 2019

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-3...

January 29, 2019

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 l...

March 6, 2018

What is the number of moles of KF in a 29-gram sample of the compound?

(1) 1.0 mol

(2) 2.0 mol

(3) 0.50 mol

(4) 5.0 mol 

Answer and Solution:

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. Th...

December 16, 2017

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/T...

December 1, 2017

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.

...

November 29, 2017

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...

November 12, 2017

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...

November 10, 2017

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 gen...

November 7, 2017

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 conduct...

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