Atoms and molecules are the building blocks of ___ and ___.

Matter and substances

True or False: The concept of atoms was experimentally validated by Maharishi Kanad and Pakudha Katyayama.

False. Their ideas were philosophical and lacked experimental validation until later.

What significant contribution did Antoine L. Lavoisier make to chemistry?

He established the foundation of chemical sciences by formulating two important laws of chemical combination.

What does the Law of Conservation of Mass state?

The Law of Conservation of Mass states that mass can neither be created nor destroyed in a chemical reaction.

In a chemical substance, the elements are always present in ___ proportions by mass.

Definite

True or False: According to John Dalton's Atomic Theory, all atoms of different elements are identical in mass and properties.

False. Atoms of different elements have distinct masses and properties.

What was the primary contribution of John Dalton to the field of chemistry?

He  formulated the atomic theory, by explaining the Law of Conservation of Mass and the Law of Definite Proportions.

Fill in the blank: Atoms are the defining structure of an element and cannot be broken by ___ means.

Chemical

True or False: The International Union of Pure and Applied Chemistry (IUPAC) approves element names and symbols based solely on their historical origins.

False. IUPAC approves element names and symbols based on standardized formats that ensure clarity and consistency, not just historical origins.

The atomic mass unit (AMU) is defined as ___ of the mass of a carbon-12 atom.

1/12

What defines a molecule and what is its smallest unit capable of independent existence?

A molecule is the smallest particle of an element or a compound that can exist independently and shows all the properties of that substance.

True or False: All elements exist independently as single atoms.

False. Most elements do not exist independently; they form molecules or ions.

Atoms of different elements combine in definite proportions to form ___ of compounds.

Molecules

True or False: A cation is a negatively charged ion.

False. A cation is a positively charged ion.

What is the significance of valency in writing chemical formulae?

Valency determines how atoms of an element combine with atoms of another element to form a chemical compound.

What is the chemical formula for Carbon Tetrachloride and how is it derived?

The chemical formula for Carbon Tetrachloride is CCl₄. It is derived from the valency of carbon, which is 4, and chlorine, which is 1, resulting in the formula CCl₄ through the crossover of their valencies.

True or False: The formula for Magnesium Chloride is Mg₄Cl₂.

False. The correct formula for Magnesium Chloride is MgCl₂, derived from magnesium's valency of 2 and chlorine's valency of 1.

Fill in the blank: The formula of Magnesium Chloride involves the crossover of the valencies of ___ and ___.

Magnesium and chlorine

What is the molecular mass of water (H₂O) calculated from its constituent atomic masses?

The molecular mass of water is 18u, calculated as 2 × 1u (for hydrogen) + 16u (for oxygen).

The formula unit mass of CaCl₂ is calculated as the sum of the atomic masses of which elements?

The formula unit mass of CaCl₂ is calculated as the atomic mass of calcium (40u) plus twice the atomic mass of chlorine (2 × 35.5u), totaling 111u.