Science 10 Chemistry Final Exam Review

WHMIS symbols represent various hazards in the lab. The WHMIS symbol that indicates a substance that is immediately toxic is (a)  

• Biohazardous Infectious Material

• Corrosive Material

• Poisonous and Infectious (Acute Tox

• Flammable Material

Answer explanation

The WHMIS symbol for substances that are immediately toxic is 'Poisonous and Infectious (Acute Tox)'. This symbol indicates a high risk of severe health effects upon exposure.

Thompson's "plum pudding" model of the atom is best described as (a)  

• A nucleus surrounded by electrons

• Electrons embedded in a positively

• Electrons orbiting the nucleus in d

• A cloud of electrons around a posit

Answer explanation

Thompson's "plum pudding" model describes the atom as having electrons embedded in a positively charged 'soup' or matrix, rather than orbiting a nucleus or existing in a cloud, which aligns with the correct choice.

Tags

NGSS.MS-PS1-1

Match the following descriptions with the correct number of protons, neutrons, and electrons in a sodium ion (Na⁺).

• Sodium ion with more protons than neutrons, and equal electrons

• 11, 12, 10

• Sodium ion with more neutrons than protons, and fewer electrons

• 12, 11, 12

• Sodium ion with more neutrons than protons, and equal electrons

• 11, 12, 11

• Sodium ion with equal protons and neutrons, and more electrons

• 11, 11, 12

Answer explanation

A sodium ion (Na⁺) has 11 protons (atomic number), 12 neutrons (23 - 11), and 10 electrons (11 - 1 due to the positive charge). Thus, the correct choice is 11 protons, 12 neutrons, and 10 electrons.

Elements in the same group of the periodic table share similar properties because they have (a)  

• The same number of protons

• The same atomic mass

• The same number of valence electron

• The same number of electron shells

Answer explanation

Elements in the same group of the periodic table have the same number of valence electrons, which determines their chemical properties and reactivity. This is why they share similar characteristics.

Which family of elements in the periodic table is the least reactive?

• Alkali metals

• Alkaline earth metals

• Halogens

• Noble gases

Answer explanation

Noble gases, found in Group 18 of the periodic table, are the least reactive elements due to their full valence electron shells, making them stable and unlikely to form chemical bonds. In contrast, alkali metals and halogens are highly reactive.

What type of bond is formed between a metal and a non-metal?

• Covalent bond

• Hydrogen bond

• Ionic bond

• Metallic bond

Answer explanation

An ionic bond is formed when a metal transfers electrons to a non-metal, resulting in oppositely charged ions that attract each other. This is distinct from covalent, hydrogen, and metallic bonds, which involve different interactions.

Which of the following compounds is an example of a molecular compound?

• NaCl

• H₂O

• K₂SO₄

• Fe₂O₃

Answer explanation

H₂O is a molecular compound formed by covalent bonds between hydrogen and oxygen atoms. In contrast, NaCl, K₂SO₄, and Fe₂O₃ are ionic compounds, consisting of ions held together by electrostatic forces.

Tags

NGSS.MS-PS1-1

Which of the following pH levels represents a strong base?

• pH 2

• pH 5

• pH 7

• pH 12

Answer explanation

A strong base has a high pH level. Among the options, pH 12 is the only value indicating a strong base, while pH 2 and pH 5 are acidic, and pH 7 is neutral.

Match the following chemical formulas with their correct names.

• HNO₃

• Nitric acid

• H₂SO₄

• Sulfuric acid

• HCl

• Nitrous acid

• HNO₂

• Hydrochloric acid

Answer explanation

HNO₃ is commonly known as nitric acid. It is a strong acid used in various applications, including fertilizers and explosives. The other options refer to different acids: nitrous acid (HNO₂), hydrochloric acid (HCl), and sulfuric acid (H₂SO₄).

In an exothermic reaction, energy is:

• Released to the surroundings

• Absorbed from the surroundings

• Created

• Destroyed

Answer explanation

In an exothermic reaction, energy is released to the surroundings as heat. This is why the correct answer is 'Released to the surroundings', indicating that the reaction gives off energy rather than absorbing or creating it.

Tags

NGSS.HS-PS1-4