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NCERT Solutions for Class 12 Biology Chapter 8 Human Health and Disease

NCERT Solutions for Class 12 Biology Chapter 8 Human Health and Disease

Edited By Irshad Anwar | Updated on Sep 14, 2023 10:56 PM IST | #CBSE Class 12th

NCERT Solutions for Class 12 Biology Chapter 8 Human Health and Disease: In the Class 12 Biology Chapter 8 NCERT Solutions, you will see questions related to the discovery of antibiotics, synthetic plant-derived drugs, and anesthetics that have changed medical practice on the one hand and human health on the other. In the solutions for NCERT Class 12 Biology Chapter 8 Human Health and Disease, you will understand some definitions, such as that health is not just the absence of disease. It is a state of complete physical, mental, social, and psychological well-being. NCERT Solutions for Class 12 Biology Chapter 8 PDF download will be helpful in developing concepts from the questions asked in the textbook. If you are looking for the answers to any other class from 6–12, then NCERT Solutions are there for you. By referring to the NCERT Solutions for Class 12 Biology, you will be able to understand all the important concepts.

In order to study for the board exams, students can use these NCERT Solutions for Class 12. Additionally, these answers are available for free download in PDF format. It provides answers in accordance with the most recent CBSE Syllabus (2023–24) and the NCERT Textbook.

More about Human Health and Disease NCERT

After going through the human health and disease chapter, you will be able to answer the questions that are given at the end of the chapter. If you have any doubts or are not able to answer them by yourself, then Solutions for Human Health and Disease NCERT will help you understand the concept behind it. Try to solve all the questions given in the Human Health and Disease NCERT PDF, as it will help you to answer them correctly.

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Solutions for human health and disease Class 12 NCERT will also provide knowledge about the topic of the immune system. Our immune system plays a major role in preventing these diseases when we are exposed to disease-causing agents. The innate defences of our body are:

  • skin
  • saliva
  • mucous membranes
  • antimicrobial substances present in our tears
  • the phagocytic cells help block the entry of pathogens into our body

NCERT Solutions For Class 12 Biology Human Health and Disease

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NCERT Exemplar for Class 12 Biology Chapter 8 Human Health and Disease

NCERT Solutions for Class 12 Biology Chapter 8 Human Health and Disease: Solved Exercise Questions

Human Health and Disease Class 12 Questions and Answers

Q1. What are the various public health measures, which you would suggest as safeguard against infectious diseases?


Health measures as a safeguard against infectious diseases

The public health measures that can be taken to avoid infectious diseases are as follows:

  • Vaccination- The populations should be vaccinated timely and properly so that they don't develop diseases. For cholera. TB, hepatitis vaccinations are available
  • Education and awareness- Everybody should be educated or made aware of the infectious diseases so that they can protect themselves from infectious diseases
  • Sanitation- Adopting public sanitation measures is good for avoiding infectious diseases. We should maintain cleanliness in our surroundings. One should also maintain cleanliness and consume only clean drinking water and contamination-free fruits and vegetables.
  • Eradication- The vectors of diseases must be eradicated by destroying the breeding sites of many vectors.

Q2. In which way has the study of biology helped us to control infectious diseases?


Biological research and tools always have been helpful in controlling and eradicating infectious or communicable diseases. biology helps us in various ways, some of them are:

1. By using the knowledge of biology we can, know the nature of the diseases.

2. To find out the mode of transmission of disease, biology plays a very important role, for example, if a person shows symptoms like vomiting or diarrhea, the mode of transmission can be through contaminated food. and disease will take the -faecal route.

3. To provide treatment and cure the infected person by medicines.

4. provide vaccines and immunization treatment for preventing the further spread of disease.

Human Health and Disease Class 12 Questions and Answers:

Q3. How does the transmission of each of the following diseases take place?

(A) Amoebiasis


Amoebiasis- It transmits via the consumption of water and food contaminated by amoebic cysts.

(B) Malaria


Malaria- It transmits from one person to another by means of female Anopheles mosquito. When this mosquito bites a diseased person, along with blood it takes the parasite and while biting a healthy person, the parasite transfers to the healthy person.

(C) Ascariasis


Ascariasis- It transmits through food and water contaminated with eggs of the parasite.

(D) Pneumonia


Pneumonia- It transmits through droplet infection i.e. through a sneeze, cough, sharing utensils etc.

Human Health and Disease Class 12 Solutions

Q4. What measure would you take to prevent water-borne diseases?


Drinking contaminated water is one of the main reasons for water born diseases such as typhoid, cholera etc. The measures that can be taken to prevent water-borne diseases are as follows

1. To prevent these diseases we should dispose of sewage, excreta, etc. properly.

2. We should check our water reservoirs regularly.

3. We should consume clean, pure, contamination free water only.

Q5. Discuss with your teacher what does 'a suitable gene' means, in the context of DNA vaccines.


A suitable gene means that special DNA segment which can be injected into the host body to produce specific proteins. These specific proteins should be such that they can kill the particular disease-causing organism present in the host body.

Human Health and Disease Class 12 Solutions

Q6. Name the primary and secondary lymphoid organs.


Lymphoid organs are the organs in which origin, maturation and proliferation of lymphocytes occur. Lymphoid organs are of two types i.e. primary lymphoid organs and secondary lymphoid organs. In primary lymphoid organs, the origin of lymphocytes occurs. These include bone marrow and thymus.

After maturation, lymphocytes migrate to a secondary lymphoid organ-like spleen, lymph nodes, tonsils, peyer’s patches of small intestine and appendix. They provide the sites for interaction lymphocyte with antigens.

NCERT solutions for class 12 biology chapter 8 human health and disease

Q8. Differentiate the following and give examples of each:

(a) Innate and acquired immunity


Innate immunity Acquired immunity
It is a non-specific type of defence present at the time of birth and provides different kinds of barriers to the entry of foreign agents into the body. It is pathogen specific defence characterised by memory.

It remains throughout the life It is short- lived
Innate immunity is inheritable Acquired immunity is not inheritable
(b) Active and passive immunity


Active immunity Passive immunity
Active immunity develops in a person’s own body in response to an infection or any disease Passive immunity develops in a person's body when antibodies from outside are injected into the body
Active immunity does not have side effects It may have side effects
It is long lasting It has a short span
Active immunity takes a long period to provide show effect Passive immunity immediately shoe effects and provides relief
Q9. Draw a well-labelled diagram of an antibody molecule.


The well-labelled diagram of an antibody molecule is as follows:


Q10. What are the various routes by which transmission of human immunodeficiency virus takes place?


Acquired immunodeficiency syndrome is caused by the human immunodeficiency virus. The various routes by which transmission of human immunodeficiency virus takes place are:

1. Through sharing of infected needles.

2. Having sex with an infected person without using condoms.

3. Infected mother to baby through the placenta.

4. Through the transfer of blood from an infected person to normal person

Human Health and Disease Class 12 NCERT Solutions

Q11. What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?


AIDS is a viral disease caused by the HIV virus. It is considered to be one of the most dangerous diseases with no cure until now. HIV affects the immune system of the body and makes it unable to perform its usual functions. The mechanism by which HIV virus causes deficiency of the immune system is as follows:

1. After entering into the system, HIV binds itself to the surface receptors present on helper T-cell and introduces its RNA and reverse transcriptase enzyme into these cells.

2. After this, by utilizing the host cell's machinery, HIV produces a copy of DNA itself through reverse transcription.

3. This copy of DNA gets incorporated into the genome of the host cell. This is called the provirus form, which directs the viral genome to produce new virus particles.

4. The subsequent formation and release of viral particles destroy the host cell. As a result, the number of T helper cells decreases.

5. AIDS occurs when the count of helper T-cells falls very much and the body is unable to fight against diseases.

Human Health and Disease Class 12 NCERT Solutions

Q12. How is a cancerous cell different from a normal cell?


Differences between cancerous cells and normal cells

Cancer cells Normal cells
Cancerous cells divide at a faster rate forming a mass of cells called tumour Normal cells divide at a normal rate and do not cause the formation of tumors
They spread, move to another tissue and affects their normal functions. Thus, they are not restricted to one location These are restricted to one location
Q13 . Explain what is meant by metastasis.


Metastasis- It refers to the process of formation of secondary tumors from the fragments of primary tumors. The pieces of primary tumors are carried to neighbouring tissues via blood. Metastasis is the last stage of cancer.

Q14. List the harmful effects caused by alcohol/drug abuse.


Harmful effects caused by alcohol/drug abuse

1. These reduce the efficiency of all the tissues of our body. Long time use of drugs and alcohol can cause many mental and physical diseases.

2. These dilate the blood vessels and affect the normal functioning of the heart.

3. Excessive drug/alcohol abuse can lead to cirrhosis in the liver.

4. Excessive drug/alcohol abuse may increase the workload of kidneys and causes kidney failure.

5. Long time use of alcohols /drugs can cause impotence.

6. Alcoholics lose their image in society because of their nature created under the influence of alcohols.

7. Drug/alcohol abuse increases family violence which affects their family and social life.

Q15. Do you think that friends can influence one to take alcohol/drugs? If yes, how may one protect himself/herself from such an influence?


Yes, friends can influence one to take alcohol/drugs. However, we can avoid those conditions in the following ways:

1. We should avoid the company of those friends who take drugs or alcohols.

2. We should increase our will power to stay away from these things.

3. We should have knowledge about the bad results of taking alcohols or drugs.

4. We should take the help of our parents if any question arises in our mind regarding this.

5. We should immediately consult a doctor if any symptoms like depression or frustration felt.

Class 12 Biology Chapter 8 NCERT Solutions

Q17 . In your view what motivates youngsters to take to alcohol or drugs and how can this be avoided?


There are several reasons which motivate youngsters to take alcohol. Some of these are given hereunder:

1. Appreciation from friends on the use of such things.

2. Sometimes youngsters start taking these things just for pleasure

3. To get rid of depression and frustration, youngsters often move to drugs/alcohol.

4. After watching it in movies, adolescents think that taking alcohol or drugs is a sign of being cool and royal. So, they also start following these.

5. Some times the company of wrong friends makes us alcoholic.

We can avoid all these, by sharing our problems with our parents. We should understand the bad effects of alcohols and should not look at alcohols as a sign of royalty or greatness. There are many other ways to solve problems other than alcohol intake. Youngsters should be taught about the moral values.

Class 12 Biology Chapter 8 NCERT Solutions:

Q7. Expand well-known abbreviations



MALT- Mucosal Associated Lymphoid Tissue

(b) CMI


CMI- Cell Mediated Immunity

(c) AIDS


AIDS- Acquired Immuno Deficiency Syndrome

(d) NACO


NACO- National AIDS Control Organisation

(e) HIV


HIV- Human Immunodeficiency Virus

Human Health and Disease Class 12 questions and answers:

Q16. Why is that once a person starts taking alcohol or drugs, it is difficult to get rid of this habit. Discuss it with your teacher.


Once a person starts taking alcohols or drug, it becomes very difficult to get rid of this habit. It is mainly because according to this person, alcohol is the only way to attain a normal state. Alcohol does not affect any organ other than the nervous system of a human body.

However, due to the effect on the nervous system other organs also get affected. Prolonged use of alcohol can make a person so addicted that his nervous system works normally only in the presence of alcohol or drugs. Even when someone starts withdrawing alcohol or drugs, the body gets affected badly and withdrawal symptoms are seen. Due to these, withdrawal symptoms, people often do not get rid of alcohol.

Helpful tips for the prevention of diseases:

  1. Personal cleanliness and hygiene
  2. Public health measures like proper disposal of waste
  3. Decontamination of drinking water
  4. Control of vectors like mosquitoes
  5. Immunization
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NCERT Solutions for Class 12 Biology Chapter 8 – Human Health and Diseases

Chapter 8 Human Health and Disease Class 12 NCERT Solutions Biology are categorised under the Unit – Biology in Human Welfare following the latest CBSE Syllabus for the session 2023-24. According to previous trends, the unit has three chapters and is worth 14 marks. In this unit, students can anticipate a sizable number of questions. Therefore, in order to be able to answer any question, especially High Order Thinking Skills (HOTS) questions, which evaluate students' reasoning abilities, students must carefully read through the NCERT Solutions of all the chapters including Class 12 biology chapter 8 question answer.

The term "human health" can be used to describe a person's social, physical, and mental well-being. In this chapter, a brief discussion of its significance and various diseases is provided. There is also discussion in Biology Chapter 8 Class 12 about the idea of drug abuse and some fatal diseases like AIDS and cancer. To learn more deeply, consult the NCERT Solutions for Ch 8 Biology Class 12, which were created by subject specialists.

Important topics of NCERT solutions for class 12 biology chapter 8 human health and disease:

Important Topics in NCERT Solutions for Class 12 Biology Human Health and Disease:

Topic Name
Human Health and Disease
8.1Common Diseases in Humans
8.5Drugs and Alcohol Abuse
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Important subtopics covered in Human Health and Disease NCERT solutions:

  • 8.1 - Common Diseases in Humans
  • 8.2 - Immunity
  • 8.2.1 - Innate Immunity
  • 8.2.2 - Acquired Immunity
  • 8.2.3 - Active and Passive Immunity
  • 8.2.4 - Vaccination and Immunisation
  • 8.2.5 - Allergies
  • 8.2.6 - Auto Immunity
  • 8.2.7 - Immune System in the Body
  • 8.3 - AIDS
  • 8.4 - Cancer
  • 8.5 - Drugs and Alcohol Abuse
  • 8.5.1 - Adolescence and Drug/Alcohol Abuse
  • 8.5.2 - Addiction and Dependence
  • 8.5.3 - Effects of Drug/Alcohol Abuse
  • 8.5.4 - Prevention and Control
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Highlights of NCERT Solutions Class 12 Biology Chapter 8 – Human Health and Disease

Class 12 biology Chapter 8 NCERT Solutions highlights are given below:

  • Human health and disease NCERT Solutions are written in the best possible way using simple language that makes solutions easier to read and understand
  • In the human health and disease Class 12 PDF, points are used to frame answers to help understand quickly.
  • Solution content for chapter 8 Biology Class 12 is derived from the textbook by the subject expert.
  • Solutions given in the human health and disease PDF are as per the latest CBSE Syllabus and guidelines.
  • human health and disease Class 12 PDF download links are readily available and easily accessible for free.
  • Important topics are listed in the Human Health and Disease Class 12 NCERT PDF.
  • NCERT human health and disease pdf is a great resource for information.
  • Diagrams are simple to understand and follow in human health and disease Class 12 NCERT solutions.

NCERT Exemplar Class 12 Solutions:

Also Check NCERT Books and NCERT Syllabus here:

NCERT Solutions for Class 12 Biology- Chapter wise

NCERT Solutions for Class 12- Subject wise

We hope that these NCERT Solutions for Class 12 Biology Chapter 8 Human Health and Disease will help you to score well in Board Examination and others.

Frequently Asked Question (FAQs)

1. What are the important topics of human health and disease ncert?

Given below are the important topics of Class 12 Biology Chapter 8:

  • Immunity  
  • Innate Immunity   
  • Acquired Immunity   
  • Active and Passive Immunity   
  • Vaccination and Immunisation   
  • Allergies   
  • Auto Immunity   
  • Immune System in the Body   
  • AIDS   
  • Cancer   
  • Drugs and Alcohol Abuse   
  • Adolescence and Drug/Alcohol Abuse   
  • Addiction and Dependence   
  • Effects of Drug/Alcohol Abuse 
  • Prevention and Control  
2. What are the various routes by which transmission of HIV takes place given Chapter 8 of NCERT Solutions for Class 12 Biology?

As per human health and disease ncert, these are the routes through which transmission of HIV can take place:

  • through sexual contact with multiple partners
  • sexual contact with an infected person.
  • due to the transfusion of the blood of an infected person
  • sharing of needles and syringes of AIDS-infected person
  • breastfeeding of an infected mother to her infant.
3. What are the primary lymphoid organs mentioned in NCERT Solutions for Class 12 Biology Chapter 8?

Primary lymphoid organs:

  • the bone marrow
  • the thymus
4. According to human health and disease ncert, what measure we need to take to prevent water-borne diseases?

These are the measures which we need to take to prevent waterborne disease:

  • proper disposing of sewage
  • allow only treated water into water reservoirs
  • disinfecting water reservoirs
  • drink only purified and boiling water
5. How to download solutions for human health and disease ncert?

To download human health and disease ncert pdf, students can use the online webpage to pdf converter tools. To Score Well in the examination, follow the NCERT syllabus and exercise given in the NCERT Book. To practice more problems, students can refer to the NCERT exemplar. 

6. Explain metastasis covered in Chapter 8 of NCERT Solutions for Class 12 Biology.

Malignant tumours exhibit the pathological process of metastasis. This process involves the cancerous cells spreading to various body parts and dividing uncontrollably to form a mass of cells known as a tumour. Some of these tumour cells are able to shed off and make their way into the bloodstream, where they travel to far-off areas of the body, where they begin to actively divide and start new tumours. 


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Questions related to CBSE Class 12th

Have a question related to CBSE Class 12th ?

Here are some options you can explore to get admission in a good school even though admissions might be closed for many:

  • Waitlist: Many schools maintain waitlists after their initial application rounds close.  If a student who secured a seat decides not to join, the school might reach out to students on the waitlist.  So, even if the application deadline has passed,  it might be worth inquiring with schools you're interested in if they have a waitlist and if they would consider adding you to it.

  • Schools with ongoing admissions: Some schools, due to transfers or other reasons, might still have seats available even after the main admission rush.  Reach out to the schools directly to see if they have any open seats in 10th grade.

  • Consider other good schools: There might be other schools in your area that have a good reputation but weren't on your initial list. Research these schools and see if they have any seats available.

  • Focus on excelling in your current school: If you can't find a new school this year, focus on doing well in your current school. Maintain good grades and get involved in extracurricular activities. This will strengthen your application for next year if you decide to try transferring again.

Best CBSE schools in Delhi: Click Here

In India, the design and coding fields offer exciting career options that can leverage your interest in both. Here's how you can navigate this path:

Choosing Your Stream:

  • Graphic Design Focus: Consider a Bachelor's degree in Graphic Design or a design diploma. Build a strong portfolio showcasing your creative skills. Learn the basics of HTML, CSS, and JavaScript to understand web development better. Many online resources and bootcamps offer these introductory courses.

  • Coding Focus: Pursue a Computer Science degree or a coding bootcamp in India. These programs are intensive but can equip you with strong coding skills quickly. While building your coding prowess, take online courses in graphic design principles and UI/UX design.

Engineering Subjects (for a Degree):

  • Information Technology (IT): This offers a good mix of web development, networking, and database management, all valuable for web design/development roles.

  • Human-Computer Interaction (HCI): This is a specialized field that bridges the gap between design and computer science, focusing on how users interact with technology. It's a perfect choice if you're interested in both aspects.

  • Passing NIOS in October 2024 will make you eligible for NIT admissions in 2025 . NIT admissions are based on your performance in entrance exams like JEE Main, which typically happen in January and April. These exams consider the previous year's Class 12th board results (or equivalent exams like NIOS).

Here's why 2025 is more likely:

  • JEE Main 2024 Admissions: The application process for NITs through JEE Main 2024 is likely complete by now (May 2024). They consider your 2023 Class 12th marks (CBSE in this case).
  • NIOS Results: Since NIOS results typically come out after the NIT admission process, your October 2024 NIOS marks wouldn't be available for JEE Main 2024.

Looking Ahead (2025 Admissions):

  • Focus on JEE Main: Since you have a computer science background, focus on preparing for JEE Main 2025. This exam tests your knowledge in Physics, Chemistry, and Mathematics, crucial for engineering programs at NITs.
  • NIOS Preparation: Utilize the time between now and October 2024 to prepare for your NIOS exams.
  • Eligibility Criteria: Remember, NITs typically require a minimum of 75% marks in Class 12th (or equivalent) for general category students (65% for SC/ST). Ensure you meet this criteria in your NIOS exams.

Yes, scoring above 99.9 percentile in CAT significantly increases your chances of getting a call from IIM Bangalore,  with your academic background. Here's why:

  • High CAT Score: A score exceeding  99.9 percentile is exceptional and puts you amongst the top candidates vying for admission. IIM Bangalore prioritizes  CAT scores heavily in the shortlisting process.

  • Strong Academics: Your 96% in CBSE 12th and a B.Tech degree demonstrate a solid academic foundation, which IIM Bangalore also considers during shortlisting.

However, the shortlisting process is multifaceted:

  • Other Factors: IIM Bangalore considers other factors beyond CAT scores, such as your work experience (if any), XAT score (if you appear for it), academic diversity, gender diversity, and performance in the interview and Written Ability Test (WAT) stages (if shortlisted).

Here's what you can do to strengthen your application:

  • Focus on WAT and PI: If you receive a shortlist, prepare extensively for the Written Ability Test (WAT) and Personal Interview (PI). These stages assess your communication, soft skills, leadership potential, and suitability for the program.

  • Work Experience (if applicable): If you have work experience, highlight your achievements and how they align with your chosen IIM Bangalore program.

Overall, with a stellar CAT score and a strong academic background, you have a very good chance of getting a call from IIM Bangalore. But remember to prepare comprehensively for the other stages of the selection process.


Yes you can appear for the compartment paper again since CBSE gives three chances to a candidate to clear his/her exams so you still have two more attempts. However, you can appear for your improvement paper for all subjects but you cannot appear for the ones in which you have failed.

I hope this was helpful!

Good Luck

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A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

Option 2)

0.16\; J

Option 3)

1.00\; J

Option 4)

0.67\; J

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

Option 2)

 6.45×10−3 kg

Option 3)

 9.89×10−3 kg

Option 4)

12.89×10−3 kg


An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

Option 2)

200 \, \, J - 500 \, \, J

Option 3)

2\times 10^{5}J-3\times 10^{5}J

Option 4)

20,000 \, \, J - 50,000 \, \, J

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)


Option 2)

\; K\;

Option 3)


Option 4)


In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced

Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)


Option 2)

3.125 × 10-2

Option 3)

1.25 × 10-2

Option 4)

2.5 × 10-2

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

Option 2)

increase two fold

Option 3)

remain unchanged

Option 4)

be a function of the molecular mass of the substance.

With increase of temperature, which of these changes?

Option 1)


Option 2)

Weight fraction of solute

Option 3)

Fraction of solute present in water

Option 4)

Mole fraction.

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

Option 2)

6.023 × 1022

Option 3)

half that in 8 g He

Option 4)

558.5 × 6.023 × 1023

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

Option 2)

more than 3 but less than 6

Option 3)

more than 6 but less than 9

Option 4)

more than 9

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