⚗️ Grade 9 Science · Chemistry

Samacheer Class 9 Science - Applied Chemistry

Free Content
Textbook Exercises
10 Sections
19 Questions

Complete Grade 9 Science questions and answers for Applied Chemistry. Click any question to expand the answer.

Share on WhatsApp
📋 Sections in this chapter
I. Choose the Correct AnswerII. Fill in the BlanksIII. Match the FollowingIV. Answer BrieflyV. Answer in DetailVI. Higher Order Thinking SkillsVII. Intext ActivitiesActivity – 1VIII. Additional ConceptsIX. Important Summary
📝 Don't just read — test yourselfFree flashcards + scored self-test · no sign-in
Your Progress — Applied Chemistry0% complete
1I. Choose the Correct Answer10 questions

Q.1One nanometre is
✓ Answer
  • (a) (10^{-7}) metre
  • (b) (10^{-8}) metre
  • (c) (10^{-6}) metre
  • (d) (10^{-9}) metre

Answer:
(d) (10^{-9}) metre

One nanometre is one billionth of a metre.

Q.2Antibiotic penicillin is obtained from
✓ Answer
  • (a) plant
  • (b) microorganism
  • (c) animal
  • (d) sunlight

Answer:
(b) microorganism


Q.31% solution of iodoform is used as
✓ Answer
  • (a) antipyretic
  • (b) antimalarial
  • (c) antiseptic
  • (d) antacid

Answer:
(c) antiseptic


Q.4Cathode reaction involves
✓ Answer
  • (a) oxidation
  • (b) reduction
  • (c) neutralisation
  • (d) catenation

Answer:
(b) reduction

Cathode is the site of gain of electrons.

Q.5Age of dead organisms can be determined using isotope of
✓ Answer
  • (a) carbon
  • (b) iodine
  • (c) phosphorus
  • (d) oxygen

Answer:
(a) carbon

Carbon-14 isotope is used.

Q.6Which does not contain natural dye?
✓ Answer
  • (a) Potato
  • (b) Beetroot
  • (c) Carrot
  • (d) Turmeric

Answer:
(a) Potato


Q.7Which nutrient protects from deficiency diseases?
✓ Answer
  • (a) Carbohydrates
  • (b) Vitamins
  • (c) Proteins
  • (d) Fats

Answer:
(b) Vitamins


Q.8Radiochemistry deals with
✓ Answer
  • (a) oxidants
  • (b) batteries
  • (c) isotopes
  • (d) nanoparticles

Answer:
(c) isotopes


Q.9Group responsible for colour of organic compounds is called
✓ Answer
  • (a) isotopes
  • (b) auxochrome
  • (c) chromogen
  • (d) chromophore

Answer:
(d) chromophore


Q.10Chlorinated hydrocarbons are used as
✓ Answer
  • (a) fertilizers
  • (b) pesticides
  • (c) food colourants
  • (d) preservatives

Answer:
(b) pesticides



2II. Fill in the Blanks5 questions

Q.1______ is an electrochemical cell which converts electrical energy into chemical change (reaction).
✓ Answer

Answer: Electrolytic cell


Q.2Painkiller drugs are called ______.
✓ Answer

Answer: analgesics


Q.3Indigo is a ______ dye.
✓ Answer

Answer: vat


Q.4______, ______ and ______ are macronutrients required for plant growth.
✓ Answer

Answer: Nitrogen, phosphorus and potassium


Q.5______ is a chemical used in finger print analysis.
✓ Answer

Answer: Ninhydrin



3III. Match the Following0 questions
List IList II
AntipyreticsFever
Corrosion preventionElectroplating
HyperthyroidismIodine-131
NanoparticleLarge surface area
ProteinsBody building


4IV. Answer Briefly4 questions

Q.1What is Radiocarbon Dating?
✓ Answer

Answer:

Radiocarbon dating is method used to determine age of fossils and dead organisms using radioactive isotope:

$$^{14}C$$

(Carbon-14)


Q.2What are Anaesthetics?
✓ Answer

Answer:

Drugs causing temporary loss of sensation are called anaesthetics.


Types

  • General anaesthetics
  • Local anaesthetics

Q.3Need for Chemical Fertilizers
✓ Answer

Answer:

Chemical fertilizers supply essential nutrients required for healthy plant growth.

Macronutrients:

  • Nitrogen
  • Phosphorus
  • Potassium

Q.4What is Forensic Chemistry?
✓ Answer

Answer:

Application of chemistry in crime investigation is called forensic chemistry.

It helps in:

  • fingerprint analysis
  • poison detection
  • blood analysis
  • drug identification


5V. Answer in Detail2 questions

Q.1Types of Dyes Based on Application
✓ Answer

# (i) Acid Dyes

  • Acidic in nature
  • Used for wool and silk

Examples:

  • Picric acid
  • Naphthol yellow-S

# (ii) Basic Dyes

Contain basic groups like:

$$-NH_2,\ -NHR,\ -NR_2$$

Examples:

  • Crystal violet
  • Methylene blue

# (iii) Mordant Dyes

Require mordant before dyeing.

Mordants:

  • Aluminium salts
  • Chromium salts
  • Iron salts

Example:

Alizarin


# (iv) Direct Dyes

Used directly on cotton and rayon.

Example:

Congo red


# (v) Vat Dyes

Used mainly for cotton.

Example:

Indigo


Q.2Food Additives and Their Functions
✓ Answer
Food AdditiveFunction
PreservativesPrevent spoilage
Colouring agentsImprove appearance
Flavouring agentsImprove taste
SweetenersAdd sweetness
AntioxidantsPrevent oxidation
EmulsifiersStabilize mixtures


6VI. Higher Order Thinking Skills3 questions

Q.1Can Watch Batteries be Recharged?
✓ Answer

No, watch batteries cannot be recharged. Watch batteries are typically primary cells, which means they contain chemical reactions that are irreversible. Once the chemical reactants in a primary cell are consumed, the battery cannot be restored to its original state by applying an external electric current, and therefore cannot be recharged. In contrast, mobile phone batteries use secondary cells, specifically lithium-ion batteries, which contain reversible chemical reactions. The reversible nature of the chemical reactions in secondary cells allows them to be recharged multiple times by applying an external electric current, which reverses the chemical reaction and restores the battery's ability to produce electrical energy. This fundamental difference between primary and secondary cells explains why watch batteries are disposable while mobile phone batteries can be used repeatedly.

Q.2Sudha met with a fire accident. What kind of drug(s) must she take?
✓ Answer

Answer:

  • Antibiotic ointments → prevent infection
  • Analgesics → reduce pain
  • Antiseptic creams → protect wounds

Q.3Fertilizer for Soil with pH 5
✓ Answer

Soil with a pH of 5 is acidic soil, which requires treatment to raise its pH to a more neutral level suitable for most crops. Agricultural lime, such as calcium carbonate (CaCO₃) or quicklime (CaO), should be added to the acidic soil to neutralize the excess acidity and raise the soil pH. Calcium carbonate reacts with the acidic compounds in the soil and gradually increases the pH over time, while quicklime acts more rapidly. When adding lime to acidic soil, it is important to avoid using acid-forming fertilizers such as ammonium sulphate, as these would counteract the liming process and further acidify the soil. After the soil pH has been raised to an appropriate level through liming, suitable NPK fertilizers containing nitrogen, phosphorus, and potassium can be applied according to the specific nutrient requirements of the crop being grown. This approach ensures that the soil conditions are optimized for plant growth and nutrient availability.


7VII. Intext Activities0 questions


8Activity – 10 questions

Lemon/Potato Galvanic Cell


Aim

To construct galvanic cell using lemon or potato.


Materials Required

  • Lemon or potato
  • Zinc-coated nail
  • Copper coin
  • LED bulb
  • Connecting wires

Procedure

  • Insert copper coin into lemon.
  • Insert zinc nail on opposite side.
  • Connect both to LED using wires.

Observation

  • Copper acts as cathode
  • Zinc acts as anode
  • Lemon juice acts as electrolyte
  • LED glows

Conclusion

Chemical energy converted into electrical energy.



9VIII. Additional Concepts0 questions

# Electrochemical Cell

Converts chemical energy into electrical energy.

Example:

Dry cell


# Electrolytic Cell

Converts electrical energy into chemical energy.

Example:

Electroplating


# Nanoparticles

Particles having size between:

$$1 - 100nm$$

Applications:

  • Medicine
  • Electronics
  • Cosmetics

# Antibiotics

Substances produced by microorganisms that kill harmful bacteria.

Example:

Penicillin


# Antipyretics

Reduce fever.

Example:

Paracetamol


# Analgesics

Relieve pain.

Example:

Aspirin


# Antiseptics

Prevent microbial growth on living tissues.

Example:

Tincture iodine



10IX. Important Summary0 questions

Nanometre

$$1nm = 10^{-9}m$$

Cathode

Reduction occurs.


Anode

Oxidation occurs.


Radiochemistry

Study of radioactive isotopes.


Ninhydrin

Used in fingerprint detection.


Indigo

Vat dye.


Electroplating

Used to prevent corrosion.


Brain Grain Grade 9 Science

Revise Applied Chemistry faster.

Use these expandable textbook answers for homework, quick revision, and exam preparation.

Textbook Q&AMobile FriendlyStep-by-Step
⚗️
Chemistry
← Previous
Carbon and Its Compounds
Next →
Animal Kingdom