1.
For the covalent compound, HCl, the inter-molecular forces that are acting between the molecules are ________.
Correct Answer
B. Permenant dipole-dipole
Explanation
The correct answer is permanent dipole-dipole. In HCl, the hydrogen atom has a partial positive charge and the chlorine atom has a partial negative charge due to the difference in electronegativity. This creates a permanent dipole in the molecule, and the positive end of one molecule is attracted to the negative end of another molecule, resulting in permanent dipole-dipole interactions between the HCl molecules.
2.
Which of the following are attributes of metals?
Correct Answer
B. Gerenrally high boiling and melting point for most metals, Conductor of electricity, Strong but not rigid
Explanation
Metals generally have high boiling and melting points, making them able to withstand high temperatures. They are also malleable and ductile, meaning they can be easily shaped and stretched without breaking. Additionally, metals are good conductors of electricity, allowing electric current to flow through them easily. However, metals are not brittle; they are strong but not rigid, meaning they can be deformed without breaking.
3.
Ionic compounds can conduct electricity in molten or aqueous state because of _____.
Correct Answer
B. Presence of mobile ions
Explanation
Ionic compounds can conduct electricity in molten or aqueous state because they contain ions that are free to move. In the molten or aqueous state, the ionic bonds are broken and the ions become mobile. These mobile ions can carry an electric charge and allow the flow of electricity through the compound. The presence of mobile ions enables the transfer of charge and the conduction of electricity in ionic compounds.
4.
Sillicon oxide is exists as a giant covalent molecule.
Correct Answer
B. False
Explanation
Sillicon dioxide exists as a giant covalent molecule.
5.
Which of the following forces is the strongest?
Correct Answer
A. Covalent bonds
Explanation
Covalent bonds are the strongest forces among the given options. Covalent bonds involve the sharing of electrons between atoms, creating a strong bond that holds the atoms together in a molecule. This sharing of electrons results in a stable configuration for both atoms, making covalent bonds highly stable and difficult to break. On the other hand, hydrogen bonds are weaker than covalent bonds as they involve an electrostatic attraction between a hydrogen atom and an electronegative atom. Van der Waals forces are even weaker than hydrogen bonds, arising from temporary fluctuations in electron distribution.
6.
Ionic compounds are brittle because _____.
Correct Answer
B. They are arranged in a regular shape and force applied would bring ions of the same charge together.
Explanation
Ionic compounds are brittle because they are arranged in a regular shape and force applied would bring ions of the same charge together. When a force is applied to an ionic compound, the ions of the same charge are forced closer together, causing repulsion between them. This repulsion leads to the breaking of the crystal lattice structure, resulting in the compound shattering easily.
7.
Metallic compounds can conduct electricity in molten or solid state because of _____.
Correct Answer
A. Presence of 'delocalised sea' of electrons
Explanation
Metallic compounds can conduct electricity in both their molten and solid states because of the presence of a 'delocalised sea' of electrons. In metallic bonding, the valence electrons are not localized to specific atoms but instead form a shared electron cloud that is free to move throughout the structure. This delocalized sea of electrons allows for the flow of electric current as the electrons can easily move and carry charge. This is why metallic compounds are good conductors of electricity.
8.
There are four ______ and one ______ in the compound C2H4.
Correct Answer
E. A) single covalent bond b) double covalent bonds
Explanation
The compound C2H4, also known as ethene, consists of one single covalent bond between the two carbon atoms (C2) and two double covalent bonds between each carbon atom and two hydrogen atoms (H4).
9.
The melting point of HBr is higher than that of HCl. Why is this so?
Both substances exist as _________. The molecules of HBr are bigger than Hcl, therefore there is more distortion of the electron cloud and more energy is required to overcome the weak Van der Waals forces between the HBr molecules than to overcome the weaker Van der Waals forces between HCl molecules. Thus, the MP of HBr is higher than HCl.
Correct Answer
simple covalent molecules
simple covalent structures
Explanation
The melting point of HBr is higher than that of HCl because both substances exist as simple covalent molecules or simple covalent structures. The molecules of HBr are bigger than HCl, which leads to more distortion of the electron cloud. As a result, more energy is required to overcome the weak Van der Waals forces between the HBr molecules compared to the weaker forces between HCl molecules. This higher energy requirement leads to a higher melting point for HBr.