Explanation

Air is a mix of gases, with nitrogen (78%) and oxygen (21%) being the main components.

The plus trace amounts of other gases like argon, carbon dioxide, and water vapor.

Explanation

1-Butyne is an alkyne, and the hydrogen atom attached to the triple-bonded carbon is relatively acidic due to the high s-character of the carbon involved in the triple bond.

This allows it to donate a proton (H+) in an acid-base reaction. 

Explanation

Anthracite is the hardest and most mature form of coal, containing the highest percentage of carbon (about 86–98%).

It burns cleanly with very little smoke.

It has the highest energy content among coal types.

Explanation

N2 (Nitrogen) has the highest critical temperature among the options (Helium - He and Hydrogen - H). 

Nitrogen (N2): While still lower than many other substances

It has a higher critical temperature than Helium because of stronger intermolecular forces. 

Explanation

Citric acid is commonly found in citrus fruits like oranges and lemons.

Grapes contain small amounts, but mango is not a significant source of citric acid;

It contains more malic and tartaric acids instead.

Explanation

Harvesting is the most important step in the preparation of sugar from sugarcane or sugar beets.

Sugarcane is typically harvested by hand or by machine, and sugar beets are harvested by machine.

The quality of the harvest affects the quality of the sugar produced.

Explanation

Accuracy refers to how close a measured value is to the true or accepted value.

It indicates the degree of agreement between the measured value and the true value.

Explanation

A reversible reaction is a reaction that can proceed in both the forward and reverse directions, and never goes to completion.

It is represented by a double arrow (⇌) between the reactants and products.

For example: A + B ⇌ C + D

Key Point:

• Single arrow (→): Represents an irreversible reaction, where the reaction only proceeds in one direction.

Explanation

Thermochemistry is the study of chemical reactions and the energy changes that involve heat.

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Explanation

A molecule is formed when two or more atoms chemically bond together.

While "H" represents the element hydrogen, it is a single atom and not a molecule.

A molecule of hydrogen is represented as H2, where two hydrogen atoms are bonded together.