1.
When electrons cannot be gained or lost, they are
Correct Answer
C. Shared
Explanation
When electrons cannot be gained or lost, it means that they are already balanced in an atom or molecule. In this case, the electrons are shared between atoms, forming covalent bonds. This sharing allows both atoms to have a stable electron configuration, fulfilling the octet rule. Therefore, the correct answer is "shared".
2.
A _______ bond is a bond where atoms share valence electrons
Correct Answer
C. Covalent
Explanation
A covalent bond is a bond where atoms share valence electrons. In a covalent bond, two or more atoms share electrons in order to achieve a more stable electron configuration. This type of bond is typically formed between nonmetal atoms.
3.
Covalent bonds always form between nonmetals and ____________.
Correct Answer
C. Nonmetals
Explanation
Covalent bonds are formed when two nonmetals share electrons. Nonmetals have high electronegativity, meaning they have a strong attraction for electrons. Therefore, they are more likely to share electrons with another nonmetal rather than give or receive electrons from a metal or metalloid. This sharing of electrons forms a covalent bond, where the atoms are held together by the shared electrons.
4.
Ionic bond is formed between atoms of ________ and _______.
Correct Answer
A. Metals and non-metals
Explanation
Ionic bonds are formed between atoms of metals and non-metals. In an ionic bond, one atom transfers electrons to another atom, resulting in the formation of positive and negative ions. Metals tend to lose electrons and become positively charged ions, while non-metals tend to gain electrons and become negatively charged ions. The attraction between these oppositely charged ions leads to the formation of an ionic bond.
5.
An ion is ____.
Correct Answer
C. An atom which has lost or gained electrons
Explanation
An ion is an atom that has lost or gained electrons. When an atom loses or gains electrons, it becomes electrically charged and forms an ion. This process can result in the formation of positively charged ions (cations) or negatively charged ions (anions). The loss or gain of electrons affects the overall charge of the atom, making it an ion.
6.
When sodium reacts with chlorine, sodium will______.
Correct Answer
B. Give one electron to chlorine
Explanation
When sodium reacts with chlorine, sodium will give one electron to chlorine. This is because sodium has one electron in its outermost energy level, while chlorine needs one more electron to complete its outermost energy level. Therefore, sodium donates one electron to chlorine, forming an ionic bond between them and resulting in the formation of sodium chloride.
7.
Ionic compound form______.
Correct Answer
C. Crystal lattice
Explanation
Ionic compounds form a crystal lattice structure. In a crystal lattice, positive and negative ions are arranged in a repeating pattern to maximize the attractive forces between them. This arrangement results in a strong and stable structure. The crystal lattice structure gives ionic compounds their characteristic properties such as high melting and boiling points, brittleness, and conductivity of electricity when dissolved in water or melted.
8.
What is the name given to the outer electron?
Correct Answer
A. Valence electrons
Explanation
Valence electrons refer to the outermost electrons in an atom that are involved in chemical bonding. These electrons determine the reactivity and chemical properties of an element. The term "valence" comes from the Latin word "valentia," meaning "power" or "capacity." Therefore, valence electrons are named as such because they have the power to form bonds with other atoms and participate in chemical reactions.
9.
Ions of opposite charge ______ each other easily, so they form crystal lattices
Correct Answer
A. Attract
Explanation
Ions of opposite charge attract each other easily due to the electrostatic force between them. This attraction allows them to come together and form crystal lattices.
10.
Which of it about covalent bond is true _____.
Correct Answer
C. Weak and have a low melting point
Explanation
The correct answer is "weak and have a low melting point." Covalent bonds are formed when two atoms share electrons, resulting in a strong bond. However, compared to ionic or metallic bonds, covalent bonds are weaker and have a lower melting point. This is because the shared electrons are localized between the two atoms, making it easier to break the bond and melt the substance. Covalent compounds also do not conduct electricity because the shared electrons are not free to move and carry an electric charge.
11.
Which compound has the highest melting point out of these?
Correct Answer
B. MgO
Explanation
MgO has the highest melting point out of the given compounds. This is because MgO is an ionic compound, formed by the strong electrostatic attraction between the positively charged magnesium ions and the negatively charged oxide ions. This ionic bond is very strong and requires a high amount of energy to break, resulting in a high melting point for MgO. In contrast, HCl, KCl, and KN3 are molecular compounds held together by weaker covalent bonds, resulting in lower melting points.
12.
Metallic solids are solids made entirely of _________.
Correct Answer
B. One metallic element
Explanation
Metallic solids consist of atoms of a single metallic element, sharing a common arrangement characterized by a "sea of electrons" delocalized among positively charged metal ions. This unique bonding structure imparts properties such as malleability, ductility, electrical conductivity, and luster, defining the distinctive characteristics of metallic materials.
13.
Because of the mobile electron cloud in the metallic compound they can conduct electricity.
Correct Answer
A. True
Explanation
The statement is true because metallic compounds have a mobile electron cloud, which means that the outermost electrons of the metal atoms are not bound to any specific atom and can move freely throughout the metal lattice. This mobility of electrons allows metallic compounds to conduct electricity, as the electrons can easily flow and carry electric current.
14.
Which type of bond dissolves easily in water?
Correct Answer
B. Ionic bond
Explanation
Ionic bonds easily dissolve in water because water is a polar molecule, meaning it has a positive and negative end. Ionic compounds, such as salts, have positive and negative ions that are attracted to the opposite charges of the water molecules. This attraction causes the ions to separate from each other and become surrounded by water molecules, resulting in the dissolution of the ionic bond.
15.
Definition of metallic bond
Correct Answer
C. Strong attraction between the positively charged cation and negatively charged sea of electrons
Explanation
A metallic bond is a type of chemical bond that occurs between metal atoms. In a metallic bond, there is a strong attraction between the positively charged metal cations and the negatively charged "sea" of delocalized electrons. This attraction allows the metal atoms to form a lattice structure, with the delocalized electrons moving freely throughout the lattice. This type of bonding is responsible for the unique properties of metals, such as their high electrical and thermal conductivity, malleability, and ductility.
16.
Bonding occurs because of the attractions of
Correct Answer
B. Electrons
Explanation
Bonding occurs because of the attractions of electrons. Electrons are negatively charged particles that orbit around the nucleus of an atom. During bonding, electrons are either shared or transferred between atoms to achieve a stable electron configuration. This sharing or transfer of electrons creates a bond between the atoms, allowing them to form molecules or compounds. The attractions between electrons and the positively charged nuclei of atoms are responsible for holding the atoms together in a bond.
17.
Which of it is true about the physical properties of diamond
Correct Answer
B. Very high melting point
Explanation
Diamond has a very high melting point. This is because diamond is made up of carbon atoms that are arranged in a strong and rigid lattice structure. The covalent bonds between the carbon atoms are very strong, making it difficult for the lattice to break apart and melt. As a result, diamond requires extremely high temperatures to reach its melting point, which is why it is known for its exceptional hardness and durability.
18.
Covalent compounds are
Correct Answer
A. Held together by weak intermolecular forces
Explanation
Covalent compounds are held together by weak intermolecular forces. This is because covalent compounds consist of atoms that share electrons in a covalent bond, resulting in a stable molecule. The intermolecular forces between these molecules are weaker compared to ionic or metallic compounds, as they only involve weak attractions between the molecules. These weak forces allow covalent compounds to have lower melting and boiling points compared to other types of compounds.
19.
Covalent compounds are soluble in
Correct Answer
A. Organic solvents
Explanation
Covalent compounds are soluble in organic solvents because they have similar chemical properties. Organic solvents are typically non-polar or have a low polarity, which allows them to dissolve other non-polar or weakly polar substances, such as covalent compounds. Water, on the other hand, is a polar solvent and is more suitable for dissolving ionic or polar compounds. Non-polar solvents, as the name suggests, are not compatible with covalent compounds as they lack the necessary polarity to dissolve them effectively.
20.
Alloys are usually harder stronger than pure metals.
Correct Answer
A. True
Explanation
Alloys are usually harder and stronger than pure metals because they are made by combining two or more metals or a metal with a non-metal. The addition of different elements in the alloy changes its structure, resulting in improved mechanical properties such as increased hardness and strength. This is due to the formation of solid solutions, intermetallic compounds, or the presence of different crystal structures, which enhance the alloy's resistance to deformation and make it more durable compared to pure metals.