Question 1

Which of the following correctly describes the location and charge of the three subatomic particles in an atom?

Accepted Answer

Protons: positive, nucleus; Neutrons: neutral, nucleus; Electrons: negative, orbitals

Question 2

Which of the following is the correctly 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 in laboratory and industrial settings?

Accepted Answer

To comply with the law of conservation of mass, ensuring the number of atoms of each element is the same 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

$$0.25\ \mathrm{M}$$

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, which element is it?

Accepted Answer

Oxygen

Question 7

Which of the following best explains what happens to the total mass during a chemical reaction?

Accepted Answer

The total mass remains constant because atoms are neither created nor destroyed

Question 8

Given the unbalanced equation: $$\mathrm{H_2$ + O_2$ \rightarrow H_2O}$$, what is the first step to balance it?

Accepted Answer

Count the number of atoms of each element on both sides

Question 9

A student mixes hydrogen and oxygen gases in a 2:1 molar ratio. According to the balanced equation $$\mathrm{2H_2 + O_2$ \rightarrow 2H_2O}$$, which reactant will be completely consumed first?

Accepted Answer

Oxygen

Question 10

Which part of the atom contains most of its mass?

Accepted Answer

Nucleus

Question 11

If you have 1 mole of $$\mathrm{H_2$}$$ and 1 mole of $$\mathrm{O_2$}$$, how many moles of water can be produced according to the balanced equation $$\mathrm{2H_2 + O_2$ \rightarrow 2H_2O}$$?

Accepted Answer

1 mole (limited by $$\mathrm{H_2$})$$

Question 12

Which statement about electrons is correct?

Accepted Answer

Electrons are found in orbitals around the nucleus and have a negative charge

Question 13

A chemist needs to prepare 0.5 M NaCl solution. How many moles of NaCl are required for 2 liters of solution?

Accepted Answer

$$1$$ mole

Question 14

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

Accepted Answer

To increase the speed of the reaction

Question 15

In the reaction $$\mathrm{2H_2 + O_2$ \rightarrow 2H_2O}$$, what is the ratio of hydrogen molecules to water molecules produced?

Accepted Answer

1:1

Question 16

Which of the following best describes a neutron?

Accepted Answer

Located in the nucleus, neutral charge

Question 17

A solution contains 0.5 mol NaCl in 2 liters. What is the concentration in mol/L?

Accepted Answer

$$0.25\ \mathrm{mol/L}$$

Question 18

Which of the following is a correct statement about protons?

Accepted Answer

Protons are positively charged and found in the nucleus

Question 19

If a chemical equation is not balanced, which law is being violated?

Accepted Answer

Law of conservation of mass

Question 20

Which of the following best describes the nucleus of an atom?

Accepted Answer

Contains protons and neutrons

Atoms, Subatomic Particles, and Chemical Equations – Guided Study

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