⚗️ Grade 9 Science · Chemistry

Samacheer Class 9 Science - Applied Chemistry

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Textbook Exercises
10 Sections
19 Questions

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

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📋 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
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 Blanks0 questions
  • Electrolytic cell converts electrical energy into chemical energy.
  • Painkiller drugs are called analgesics.
  • Indigo is a vat dye.
  • Nitrogen, phosphorus and potassium are important macronutrients.
  • Ninhydrin is used in fingerprint analysis.


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

Answer:

No.

Watch batteries are usually:

Primary cells

Their chemical reactions are irreversible.

Hence they cannot be recharged.


Mobile Phone Batteries

Mobile phones use:

Secondary cells

(Lithium-ion batteries)

Their reactions are reversible.

Hence they can be recharged.


Q.2Drugs Required for Burn Injuries
✓ Answer

Answer:

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

Q.3Fertilizer for Soil with pH 5
✓ Answer

Answer:

pH 5 indicates acidic soil.

Hence alkaline/basic fertilizers should be used.

Examples:

  • Potash fertilizers
  • Lime-containing fertilizers


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.


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