Periodic Table — Set 1
Chemistry · आवर्त सारणी · Questions 1–10 of 40
Which type of chemical bond involves the complete transfer of electrons from one atom to another?
Correct Answer: B. Ionic bond
An ionic bond is formed when one atom gives up electrons to another, creating charged ions. This typically occurs between a metal and a non-metal with different electronegativities. Sodium chloride is a classic example of a substance held together by these electrostatic forces.
What is the primary reason why atoms form chemical bonds with each other?
Correct Answer: B. To achieve a stable octet configuration
Atoms bond to reach a more stable state by filling their outermost electron shell. Most atoms seek to have eight valence electrons, similar to the noble gases. This tendency is widely known as the Octet Rule in chemistry.
Which of the following molecules contains a triple covalent bond?
Correct Answer: B. Nitrogen ($N_2$)
Nitrogen atoms share three pairs of electrons to form a very strong triple bond. This high bond energy makes atmospheric nitrogen relatively inert and difficult to break apart. In contrast, oxygen molecules are held together by a double covalent bond.
What type of bond is formed when atoms share electrons equally between them?
Correct Answer: D. Non-polar covalent bond
Non-polar covalent bonds occur when two atoms have similar electronegativities and share electrons evenly. This typically happens in diatomic molecules like $H_2$ or $Cl_2$. Such bonds do not result in a partial electrical charge on either atom.
The 'Sea of Electrons' model is used to describe the bonding in which type of substances?
Correct Answer: D. Metals
Metallic bonding involves a lattice of positive ions surrounded by a mobile cloud of delocalized electrons. These free-moving electrons are responsible for the high electrical and thermal conductivity of metals. This unique structure also allows metals to be malleable and ductile.
Which of these bonds is characterized by the sharing of an electron pair where both electrons come from the same atom?
Correct Answer: C. Coordinate covalent bond
A coordinate covalent bond occurs when one atom provides both electrons for the shared pair. This is also commonly referred to as a dative bond in many chemistry textbooks. An example of this is the formation of the ammonium ion from ammonia and a hydrogen ion.
Which intermolecular force is responsible for the unexpectedly high boiling point of water?
Correct Answer: B. Hydrogen bonding
Hydrogen bonding is a strong dipole-dipole attraction that occurs when hydrogen is bonded to highly electronegative elements like oxygen. It requires more energy to break these attractions, leading to higher boiling and melting points. This force is also critical for maintaining the structure of DNA molecules.
What is the shape of a methane ($CH_4$) molecule according to the VSEPR theory?
Correct Answer: B. Tetrahedral
Methane adopts a tetrahedral shape because the four pairs of bonding electrons repel each other into this geometry. The bond angle between the hydrogen atoms is approximately 109.5 degrees. VSEPR theory helps predict molecular shapes based on electron pair repulsion.
Which property is generally characteristic of ionic compounds?
Correct Answer: B. High melting and boiling points
Ionic compounds have high melting points due to the strong electrostatic forces holding the lattice together. They do not conduct electricity as solids but do so when melted or dissolved in water. Most ionic substances are crystalline solids at room temperature.
Which of the following elements has the highest electronegativity on the Pauling scale?
Correct Answer: A. Fluorine
Fluorine is the most electronegative element, meaning it has the strongest tendency to attract shared electrons. Its value is assigned as 4.0 on the Pauling scale. Electronegativity generally increases as you move from left to right across a period.