Test: Language Of Chemistry - Class 9 MCQ

Valency refers to the combining capacity of an atom, which is determined by the number of electrons it can lose, gain, or share in chemical reactions. This property is crucial for understanding how different elements interact with one another.

One significant limitation of a chemical equation is that it does not provide information about the rate of the reaction, which can be influenced by various factors such as concentration, temperature, and the presence of catalysts. Understanding these aspects is crucial for practical applications in chemistry.

Relative atomic mass (RAM) compares the mass of an atom to 1/12th the mass of a carbon-12 atom. This unit allows chemists to easily discuss and calculate the masses of different elements in chemical reactions.

A molecular formula provides detailed information about the number of each type of atom in a molecule, while a chemical symbol identifies the element itself. For instance, H₂O indicates that there are two hydrogen atoms and one oxygen atom in a water molecule.

A radical is an atom or group of atoms that carries a positive or negative charge and behaves as a single unit in chemical reactions. Radicals play a significant role in the formation of compounds, such as in the case of ammonium (NH₄⁺).

Compounds formed by two non-metals, such as PCl₅ (phosphorus pentachloride), are named using prefixes to indicate the number of atoms of each element present in the molecule. The prefix "penta-" signifies the presence of five chlorine atoms.

The empirical formula expresses the simplest whole-number ratio of different atoms in a compound. For example, the empirical formula for hydrogen peroxide (H₂O₂) is HO, indicating a 1:1 ratio of hydrogen to oxygen.

An atom is the fundamental building block of matter and represents the smallest particle that retains all the chemical properties of an element. While molecules consist of two or more atoms bonded together, an atom itself is the basic unit of an element.

A diatomic molecule is defined as one that is composed of two atoms. Examples include hydrogen (H₂), oxygen (O₂), and nitrogen (N₂). These molecules are essential in various chemical processes like respiration and combustion.

A binary acid consists of hydrogen and one other non-metal element. HCl, or hydrochloric acid, is classified as a binary acid because it contains hydrogen and chlorine. This naming convention is important for differentiating acid types.

Reactants are the starting substances in a chemical reaction that undergo changes to form products. Understanding the reactants is essential for predicting the outcomes and stoichiometry of chemical processes.

Percentage composition provides the weight percentage of each element in a compound, calculated by dividing the total weight of the element by the molecular weight of the compound and multiplying by 100. This information is useful for understanding the elemental makeup of substances.

Phosphorus exists as a tetratomic molecule in its most common form, P₄, where four phosphorus atoms are bonded together. This contrasts with diatomic molecules like nitrogen and oxygen, which consist of two atoms.

A skeleton equation is an unbalanced representation of a chemical reaction that lists the reactants and products without ensuring that the number of atoms for each element is the same on both sides. Balancing the skeleton equation is necessary to reflect the conservation of mass.

A catalyst is a substance that accelerates a chemical reaction by lowering the activation energy required for the reaction to occur. Importantly, it is not consumed in the process and can be used repeatedly, making it essential for many industrial and biological processes.