Molecule

Overview

A molecule is the smallest particle of a pure substance that can exist independently, consisting of one or more atoms. The number of atoms present in a molecule determines its atomicity, which can be monoatomic, diatomic, triatomic, etc. Molecules of elements may contain the same type of atoms, while compounds consist of different kinds of atoms. The sizes of molecules vary depending on the number of atoms and their shapes, with some being large enough to be called macromolecules like haemoglobin, which is made up of nearly 10,000 atoms and is significantly heavier than a hydrogen atom.

Questions and Answers

1. What is a molecule?

   A molecule is the smallest particle of a pure substance that can exist independently. It may contain one or more atoms. The number of atoms present in a molecule determines its atomicity. Molecules can be monoatomic, diatomic, triatomic, etc., based on the number of atoms they contain.

2. What are macromolecules?

   Macromolecules are large molecules that can contain thousands of atoms. An example is haemoglobin found in blood, which is made up of nearly 10,000 atoms and is much heavier than a hydrogen atom.

3. What determines the size of a molecule?

   The size of a molecule depends on the number of atoms present in it and their shapes. Larger molecules are called macromolecules and can be significantly bigger than individual atoms.

4. What is the relationship between atoms and molecules?

   Atoms are the building blocks of matter, and they can combine to form molecules. Molecules, in turn, can either be made up of the same type of atoms (elements) or different types of atoms (compounds).

5. How do ions differ from molecules?

   Ions are species that carry either a positive or negative charge, formed when atoms lose or gain electrons. In contrast, molecules are neutral particles made up of atoms held together by chemical bonds.

Multiple-Choice Questions

1. Which of the following is an example of a diatomic molecule?

   a) He
   b) Cl₂
   c) O₃
   d) P₄
   Answer: b) Cl₂

2. Which of the following is a macromolecule?

   a) HCl
   b) NH₃
   c) H₂SO₄
   d) Haemoglobin
   Answer: d) Haemoglobin

3. Which type of molecule contains different kinds of atoms?

   a) Monoatomic
   b) Diatomic
   c) Triatomic
   d) Compounds
   Answer: d) Compounds

4. How many atoms are present in a diatomic molecule?

   a) One
   b) Two
   c) Three
   d) Four
   Answer: b) Two

5. What is the function of haemoglobin?

   a) Carries oxygen in the body
   b) Helps in digestion
   c) Provides energy to cells
   d) Supports brain function
   Answer: a) Carries oxygen in the body