NCERT Solutions for Class 9 Science Chapter 13 – Why Do We Fall Ill?

NCERT Solutions for Class 9 Science Chapter 13 – Why Do We Fall Ill will help you learn about conditions for good health, effects of diseases on your health, infectious diseases, immunization, precautions to prevent diseases etc. Chapter 13 of NCERT Solutions Class 9 Science deals with basic awareness about health. There are numerous kinds of exercises in the chapter which ensure that all these terms are strongly imbibed in your minds. 

Solutions for Chapter 13 – Why Do We Fall Ill, contain 4 exercises and 15 questions in total. We can help you solve these exercises easily with the help of our high-quality solutions. Our subject matter experts have created these solutions to help you understand the topics of the chapter easily. Our solutions include proper explanations and are well-structured. 

CBSE Class 9 Science Chapter 13 deals with many more topics like illness examination, recovery from diseases, methods through which these diseases can be prevented, causes of their spread, survey techniques etc. Now you can learn all these topics easily with the help of our NCERT solutions. 

Important Topics of NCERT Class 9 Chapter 13: Why Do We Fall Ill?


The process of injecting a person in order to make a person immune to certain diseases is called immunization. The ability of a person’s body to detect, destroy and eliminate external germs and components which cause diseases is known as immunity. The administering of his immunity through a vaccine is known as immunization. 

The vaccines which are used for immunization actually carry the disease-causing germs which are present in their very diluted or weakened form. These diluted diseases causing germs can either be dead or living depending upon the kind of vaccine and the disease that is being tackled. This prevents any kind of infection from the same germs with the help of microbes. 

Types of Immunization

Immunization for infants – DPT, BCG, POLIO and Measles. 

Immunization for pregnant women – TT and Hepatitis 

Means of Communication and Spread of Diseases

Diseases that are infectious in nature can spread through various mediums. Some of these mediums are – 

  1. Through Air – when an infectious person sneezes or coughs, they tend to release small droplets which carry the germs from their bodies. These droplets may travel through the air and affect another person who is healthy and cause them the same disease or infection. Pneumonia and tuberculosis are a disease which is transmitted in other healthy people through the same phenomenon 
  2. Through Water – just like diseases spread through the air, they also tend to spread through water. Usually, the water is polluted through excreta or other infectious and disease-causing elements which get washed with water. When the same water is used by other people directly or through water supplies, then diseases are caused. To prevent such cases one must always ensure that they drink purified water and use clean water for drinking purposes. Cholera and hepatitis are diseases which are spread through water. 
  3. Sexual Contact – diseases like AIDS and Syphilis are spread through sexual intercourse amongst an infected person and a healthy person, or in case of unhygienic surroundings. These diseases also tend to spread through infected syringes, infected pregnant mothers to her child etc. To prevent such circumstances there are a number of steps that can be taken. One must ensure that the hospitals dispose of used syringes and keep a check on blood donors and their medical history. 

Exercise wise discussion of NCERT Class 9 Solutions Chapter 13 – Why Do We Fall Ill?

  1. NCERT Solutions for Class 9 Science Chapter 13 – Why Do We Fall Ill? consists of a diverse set of questions. These include short answer questions, multiple-choice questions, direct theory based questions and descriptive questions. 
  2. The first exercise begins with a descriptive answer which asks about two conditions of good health. There are other similar questions which require you to state points about conditions to be free from diseases, reasons and symptoms of sickness, precautions against diseases etc. 
  3. In order to answer these questions you just need the basic knowledge of the chapter which will not just help you in scoring high in your exams but will also help you in staying aware about the disease around you. 
  4. There are also questions which require you to give definitions of immunization and health. 
  5. Also, there are questions which require you to observe and then answer about conditions like illness, different diseases, and types of diseases. These questions also require you to carry out surveys. 

About NCERT Solutions for Class 9 Science Chapter 13 – Why Do We Fall Ill? by Instasolv

  • In our NCERT Solutions for Class 9 Science Chapter 13 – Why Do We Fall Ill, we have ensured that the solutions are presented in a stepwise manner so that you learn the fundamentals and logic applied behind every answer. 
  • Our team of experts has ensured that no exercise is left and all the problems are carefully tackled. 
  • All our solutions are in accordance with the latest CBSE syllabus.