Q: Which of the following is the correct formula for calculating molarity?

$$ \mathrm{M = \frac{\text{moles\;of\;solute}}{\text{liters\;of\;solution}}} $$

Question 1

Which of the following correctly describes the three subatomic particles found in an atom?

Accepted Answer

Protons (positive charge, nucleus), Neutrons (neutral charge, nucleus), Electrons (negative charge, outside nucleus)

Question 2

Which of the following is the correct balanced chemical equation for the formation of water from hydrogen and oxygen gases?

Accepted Answer

$$ \mathrm{2H_2 + O_2$ \rightarrow 2H_2O} $$

Question 3

Why is it important to balance chemical equations?

Accepted Answer

To satisfy the law of conservation of mass, ensuring the same number of atoms of each element on both sides.

Question 4

A solution is prepared by dissolving 0.5 mol of NaCl in 2 liters of water. What is the molarity of the solution?

Accepted Answer

$$ \mathrm{0.25\;M} $$

Question 5

Which subatomic particle is responsible for the chemical properties of an element?

Accepted Answer

Electron

Question 6

If a neutral atom has 8 protons, 8 neutrons, and 8 electrons, what element is it?

Accepted Answer

Oxygen

Question 7

Which of the following best describes the location of electrons in an atom?

Accepted Answer

Electrons are found in energy levels outside the nucleus.

Question 8

A student writes the equation $$ \mathrm{H_2$ + O_2$ \rightarrow H_2O} . $$What is wrong with this equation?

Accepted Answer

It is not balanced; there are more oxygen atoms on the left than on the right.

Question 9

Which of the following is a correct statement about protons?

Accepted Answer

Protons have a positive charge and are found in the nucleus.

Question 10

A hospital prepares a saline solution by dissolving 0.9 g of NaCl in enough water to make 100 mL of solution. What is the molarity of NaCl in the solution? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$ \mathrm{0.154\;M} $$

Question 11

Which of the following is NOT a reason for balancing chemical equations?

Accepted Answer

To ensure the reaction is safe.

Question 12

Which particle determines the atomic number of an element?

Accepted Answer

Proton

Question 13

A chemical reaction produces 36 g of water. How many moles of water is this? (Molar mass of $$ \mathrm{H_2O}  = 18 g/$$mol)

Accepted Answer

$$ \mathrm{2\;mol} $$

Question 14

Which of the following best explains the role of neutrons in the atom?

Accepted Answer

Neutrons provide mass and stabilize the nucleus.

Question 15

A student mixes 1 mol of hydrogen gas with 1 mol of oxygen gas. According to the balanced equation $$ \mathrm{2H_2 + O_2$ \rightarrow 2H_2O} $$, what is the limiting reactant?

Accepted Answer

Hydrogen gas

Question 16

Which of the following is the correct formula for calculating molarity?

Accepted Answer

$$ \mathrm{M = \frac{	ext{moles\;of\;solute}}{	ext{liters\;of\;solution}}} $$

Question 17

In a chemical reaction, what does the coefficient in front of a chemical formula represent?

Accepted Answer

The number of molecules or moles involved in the reaction.

Question 18

Which of the following statements is true about the nucleus of an atom?

Accepted Answer

The nucleus contains protons and neutrons.

Question 19

A chemical reaction in a fuel cell combines hydrogen and oxygen to produce water and energy. Which balanced equation represents this reaction?

Accepted Answer

$$ \mathrm{2H_2 + O_2$ \rightarrow 2H_2O} $$

Question 20

A solution contains 0.2 mol of NaCl in 500 mL of water. What is the molarity of the solution?

Accepted Answer

$$ \mathrm{0.4\;M} $$

Atoms, Subatomic Particles, Chemical Equations, and Solution Molarity

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