1.
Chemical stucture determines what about a compound?
Correct Answer
D. It's properties
Explanation
The chemical structure of a compound determines its properties. This is because the arrangement of atoms and the types of bonds present in a compound influence its physical and chemical characteristics. For example, the presence of double bonds in a molecule can make it more reactive, while the presence of polar bonds can make a compound soluble in water. Therefore, understanding the chemical structure of a compound is crucial in predicting and explaining its behavior and properties.
2.
Forms when there are strong bonds between a positive sodium ion and a negative chlorine ion.
Correct Answer
B. Salt
Explanation
Salt forms when there are strong bonds between a positive sodium ion and a negative chlorine ion. Sodium (Na) has one valence electron and chlorine (Cl) has seven valence electrons. Sodium loses one electron to become a positively charged ion (Na+), while chlorine gains one electron to become a negatively charged ion (Cl-). The opposite charges attract each other, resulting in the formation of ionic bonds between sodium and chlorine ions. This creates a crystal lattice structure, giving salt its characteristic properties.
3.
This substance forms from silicon dioxide. The bonds that hold these atoms together are very strong
Correct Answer
D. Quartz
Explanation
Quartz is formed from silicon dioxide (SiO2), which is a compound commonly found in nature. The bonds between the silicon and oxygen atoms in quartz are very strong, resulting in a stable and durable structure. This explains why quartz is a hard and resistant mineral. In contrast, sugar, salt, and pepper do not form from silicon dioxide and do not exhibit the same strong bond characteristics as quartz.
4.
A substance formed when molecules are bonded together. Made of carbon, hydrogen and oxygen.
Correct Answer
A. Sugar
Explanation
Sugar is a substance formed when molecules are bonded together. It is made of carbon, hydrogen, and oxygen. This description accurately fits the composition of sugar, as it is a carbohydrate composed of carbon, hydrogen, and oxygen atoms.
5.
Salt has the following properties.
Correct Answer
B. High melting and boiling point
Explanation
Salt has a high melting and boiling point. This means that it requires a significant amount of heat to melt or boil salt compared to other substances. The high melting and boiling point of salt can be attributed to the strong ionic bonds between its sodium and chloride ions. These bonds require a large amount of energy to break, resulting in a high melting and boiling point for salt.
6.
Which of the following has a weaker bond?
Correct Answer
A. Sugar
Explanation
Sugar has a weaker bond compared to salt. This is because sugar is a covalent compound, meaning its atoms are held together by sharing electrons. Covalent bonds are generally weaker than ionic bonds, which hold salt together. Salt is an ionic compound, formed by the attraction between positively and negatively charged ions. Ionic bonds are stronger because of the electrostatic forces between the oppositely charged ions. Therefore, sugar has a weaker bond than salt.
7.
Quartz has the following property.
Correct Answer
B. High melting and boiling pooint
Explanation
Quartz has a high melting and boiling point. This means that it requires a high temperature to melt or boil. This property is due to the strong bonds between the atoms in the quartz structure, which require a lot of energy to break. As a result, quartz is able to withstand high temperatures without undergoing significant changes in its physical state.
8.
Which of the following substances requires the most energy to break its bonds.
Correct Answer
D. Quartz
Explanation
Quartz requires the most energy to break its bonds because it is a mineral composed of silicon and oxygen, forming a strong and stable crystal lattice structure. Breaking these bonds requires a significant amount of energy compared to the other substances listed. Sugar, salt, and pepper are organic compounds with simpler molecular structures, making their bonds easier to break.
9.
The force that holds atoms or ions together in a compound is known as:
Correct Answer
C. Chemical bond
Explanation
A chemical bond refers to the force that holds atoms or ions together in a compound. This bond is formed through the sharing, transfer, or attraction of electrons between the atoms or ions. It is the fundamental concept in chemistry that explains the formation of molecules and compounds. Chemical bonds can be covalent, ionic, or metallic, depending on the type of elements involved and the way electrons are shared or transferred. The term "chemical strength" is not commonly used to describe the force holding atoms together, while "chemical length" and "chemical structure" do not accurately represent the concept of the force itself.
10.
Of the following models which one shows the space occupied by atoms.
Correct Answer
B. Space filling model
Explanation
The space filling model shows the space occupied by atoms. In this model, the atoms are represented by spheres that are scaled to their relative sizes and are packed together to show how they fill the space. This model provides a more realistic representation of the molecule's structure, as it shows the actual spatial arrangement of atoms and their sizes. The ball-stick model, on the other hand, represents atoms as balls and bonds as sticks, focusing more on the connectivity between atoms rather than their spatial arrangement. The structural formula represents atoms and bonds using symbols and lines, providing information about the connectivity and arrangement of atoms in a molecule, but not their spatial arrangement.
11.
Of the following models which one uses chemical symbols to represent the atoms.
Correct Answer
C. Structural formula
Explanation
The structural formula model uses chemical symbols to represent the atoms. In this model, the atoms are represented by their chemical symbols and the bonds between them are represented by lines. This model provides a simplified representation of the molecular structure and allows us to see how atoms are connected to each other in a compound. The ball-stick model, on the other hand, uses balls to represent atoms and sticks to represent bonds. The space filling model represents atoms as spheres and shows their relative sizes in a molecule.
12.
Of the following which shows the structures of a compound.
Correct Answer
C. Structural formula
Explanation
The structural formula is a way to represent the arrangement of atoms in a compound. It uses lines to represent chemical bonds between atoms and shows the connectivity of the atoms in the molecule. The ball-stick model and space filling model are three-dimensional representations that show the relative sizes and positions of atoms in a compound. However, they do not provide information about the connectivity of the atoms and the arrangement of bonds in the molecule. Therefore, the correct answer is the structural formula.
13.
Of the following which represents the bond lengths and angles and the relationships between the atoms.
Correct Answer
A. Ball-stick model
Explanation
The ball-stick model is a type of molecular model that represents the bond lengths and angles between atoms in a molecule. It uses balls to represent atoms and sticks to represent the bonds between them. This model provides a visual representation of the three-dimensional structure of a molecule, showing the arrangement of atoms and the connections between them. The ball-stick model allows us to understand the relationships between atoms in terms of their bonding and spatial arrangement.
14.
Of the following which shows size.
Correct Answer
B. Space filling model
Explanation
The space filling model shows size because it represents the atoms and molecules in a three-dimensional manner, filling up the space they occupy. This model provides a more accurate depiction of the relative sizes of the atoms and molecules compared to the other options. The ball-stick model only represents the atoms as spheres and the bonds between them as sticks, while the structural formula only shows the arrangement of atoms and the bonds between them without any indication of size. Therefore, the space filling model is the most suitable option for representing size.
15.
Which of the following is not eh best way to represent a bond because it doesn't take in to account flexibility, stretch and rotation.
Correct Answer
A. Ball-stick model
Explanation
The ball-stick model is not the best way to represent a bond because it doesn't take into account flexibility, stretch, and rotation. This model only shows the atoms as balls and the bonds as sticks, without considering the actual movement and flexibility of the atoms and bonds. In contrast, the space filling model represents the atoms as spheres with their respective sizes, allowing for a more accurate representation of the bond's flexibility and rotation. The structural formula, on the other hand, uses lines and symbols to depict the arrangement of atoms and bonds, providing information about the connectivity and flexibility of the molecule.