(2) melting of copper
(3) condensation of ethanol vapor
(4) sublimation of iodine
Answer:
The correct answer is option 3.
Explanation:
Condensationof ethanol vapors is an exothermic process. This is because particles in gaseous has highest energy . Some of this energy gets released when these particles or ethanol vapors condenses into a liquid state where they have less amount of energy in comparison to gaseous state.
As we know that exothermic reaction are those reaction in which heat is released into the surroundings.
Where as the other options are example of an endothermic reaction.where heat is absorbed from the surroundings.
Hence, the correct answer is option 3.
Answer:
Explanation:
The partial negative charge in a water molecule occurs because of differences in electronegativity between the atoms involved. A water molecule (H2O) consists of two hydrogen atoms and one oxygen atom. Oxygen is significantly more electronegative than hydrogen, which means it has a stronger attraction for electrons.
In a covalent bond between hydrogen and oxygen, such as in a water molecule, electrons are shared between the two atoms. However, because oxygen is more electronegative, it pulls the shared electrons closer to itself, creating an uneven distribution of electron density. This results in the oxygen atom having a partial negative charge (δ-) and the hydrogen atoms having partial positive charges (δ+).
The electronegativity difference between hydrogen and oxygen causes the electrons in the covalent bonds to spend more time around the oxygen atom, making it partially negatively charged. This partial negative charge on the oxygen atom and the partial positive charges on the hydrogen atoms give water its polar nature. This polarity plays a crucial role in various chemical and physical properties of water, such as its ability to form hydrogen bonds, its high surface tension, and its unique solvent properties.