TVL9S - Tirunelveli District
Common Half Yearly Examination - 2024
Standard 9 - SCIENCE
Time: 3.00 Hours | Marks: 75
I. Choose the correct answer. Write it with the option. (12x1=12)
1) Rulers, measuring tapes and metre scales are used to measure.
- a) mass
- b) weight
- c) time
- d) length
Answer
d) length
2) Clouds float atmosphere because of their low
- a) density
- b) pressure
- c) velocity
- d) mass
Answer
a) density
3) Electroplating is an example for
- a) heating effect
- b) Chemical effect
- c) Flowing effect
- d) magnetic effect
Answer
b) Chemical effect
4) Transformer works on
- a) AC only
- b) DC only
- c) both AC and DC
Answer
a) AC only
5) ............. has the same properties throughout the sample
- a) Pure substance
- b) mixture
- c) colloid
- d) suspension
Answer
a) Pure substance
6) The term nucleons refer to .............
- a) Protons and electrons
- b) only neutrons
- c) electrons and neutrons
- d) Protons and neutrons
Answer
d) Protons and neutrons
7) Example for liquid metal is .............
- a) Sodium
- b) Mercury
- c) Potassium
- d) Oxygen
Answer
b) Mercury
8) Acid turn blue litmus paper to .............
- a) green
- b) orange
- c) red
- d) yellow
Answer
c) red
9) Poliomyelitis virus enters the body through .............
- a) skin
- b) mouth and nose
- c) ears
- d) eye
Answer
b) mouth and nose
10) Food and Adulteration Act was enforced by Government of India in the year .............
- a) 1964
- b) 1954
- c) 1950
- d) 1963
Answer
b) 1954
11) The structural and functional unit of the kidney is .............
- a) villi
- b) liver
- c) nephron
- d) ureter
Answer
c) nephron
12) Excretory organ of tape worm is .............
- a) flame cells
- b) nephridia
- c) body surface
- d) solenocytes
Answer
a) flame cells
II. Answer any 7 questions. (Q.No. 22 is compulsory) (7x2=14)
13) Define least count of any device
Solution
The smallest measurement that can be measured accurately by an instrument is called its least count (LC).
14) Differentiate speed and velocity
Solution
| Speed | Velocity |
|---|
| Rate of change of distance. | Rate of change of displacement. |
| It is a scalar quantity. | It is a vector quantity. |
15) Why does Helium balloon floats thin air?
Solution
Helium gas is less dense than air. Therefore, the buoyant force (upthrust) exerted by the air on the balloon is greater than the weight of the balloon, causing it to float.
16) What are electric lines of force?
Solution
Electric lines of force are imaginary lines representing the electric field. They start from a positive charge and end at a negative charge, indicating the direction of the electric field at any point.
17) State-Fleming's left hand rule?
Solution
Stretch the thumb, forefinger, and middle finger of the left hand mutually perpendicular to each other. If the forefinger points in the direction of the magnetic field and the middle finger in the direction of the current, then the thumb points in the direction of the force acting on the conductor.
18) Define Sublimation with example.
Solution
Sublimation is the process in which a solid substance changes directly into the gas phase without passing through the liquid phase.
Example: Camphor, Iodine, Dry ice.
19) Draw the structure of oxygen atom, write atomic number, mass number, proton and neutron
Solution
Atomic Number (Z): 8
Mass Number (A): 16
Number of Protons: 8
Number of Neutrons: 8
Structure:
- Nucleus contains 8 Protons and 8 Neutrons.
- K-shell (1st orbit) contains 2 electrons.
- L-shell (2nd orbit) contains 6 electrons.
20) State Modern periodic law
Solution
The physical and chemical properties of elements are periodic functions of their atomic numbers.
21) Differentiate Phototropism and Photonasty
Solution
- Phototropism: Directional growth movement of a plant part in response to light (e.g., shoot bends towards light).
- Photonasty: Non-directional movement of a plant part in response to light intensity (e.g., opening of Moonflower at night).
22) Find the oxidation number of sulphur in \(H_2SO_4\) molecule.
Solution
Let the oxidation number of Sulphur be \(x\).
Oxidation number of H = +1
Oxidation number of O = -2
$$2(+1) + x + 4(-2) = 0$$
$$2 + x - 8 = 0$$
$$x - 6 = 0$$
$$x = +6$$
The oxidation number of Sulphur is +6.
III. Answer any 7 questions. (Q.No. 32 is compulsory) (7x4=28)
23) i) Differentiate mass and weight (2)
ii) Fill ups (2)
a) Negative acceleration is called .............
b) Area under velocity - time graph shows .............
Solution
i) Mass vs Weight:
| Mass | Weight |
|---|
| Quantity of matter contained in a body. | Gravitational force exerted on a body. |
| Scalar quantity. Remains constant everywhere. | Vector quantity. Varies from place to place. |
ii) Fill ups:
a) Retardation (or Deceleration)
b) Displacement (or Distance travelled)
24) i) State Pascal's law (2)
ii) State True or False (2)
a) The weight of fluid displaced determines the buoyant force on an object
b) Hydraulic press is used in the extraction of oil from oil seeds
Solution
i) Pascal's Law:
The pressure applied to an enclosed fluid is transmitted undiminished to every point of the fluid and the walls of the container.
ii) True or False:
a) True (Based on Archimedes' Principle)
b) True (Application of Pascal's Law)
25) A bird sitting on a high power electric line is still safe, How?
Solution
When a bird sits on a single high-power line, both its feet are at the same electrical potential. Therefore, there is no potential difference between its feet. As a result, no current flows through the bird's body, keeping it safe.
26) Match (2)
- a) Magnetic material - Oersted
- b) Non-magnetic material - Iron
- c) Current and magnetism - Faraday
- d) Electromagnetic Induction - Wood
Fill ups (2)
i) The mirror used in search light is .............
ii) Large ............. mirrors are used in solar furnaces
Solution
Match Correctly:
a) Magnetic material - Iron
b) Non-magnetic material - Wood
c) Current and magnetism - Oersted
d) Electromagnetic Induction - Faraday
Fill ups:
i) Concave
ii) Concave
27) a) Define - Tyndall effect (2)
b) Differentiate - Elements and Compounds.
Solution
a) Tyndall effect:
The scattering of a beam of light by the colloidal particles present in a solution, making the path of light visible, is called the Tyndall effect.
b) Elements vs Compounds:
| Elements | Compounds |
|---|
| Made up of only one kind of atom. | Made up of more than one kind of atom chemically combined. |
| Cannot be broken down into simpler substances. | Can be broken down into elements by chemical methods. |
28) 1) Match (2)
- a) Dalton - Hydrogen atom model
- b) Chadwick - Discovery of nucleus
- c) Rutherford - First atomic theory
- d) Neils Bohr - Discovery of neutrons
2) State any four features of modern periodic law
Solution
1) Match Correctly:
a) Dalton - First atomic theory
b) Chadwick - Discovery of neutrons
c) Rutherford - Discovery of nucleus
d) Neils Bohr - Hydrogen atom model
2) Features of Modern Periodic Table:
1. Elements are arranged in increasing order of atomic numbers.
2. There are 7 horizontal rows called periods.
3. There are 18 vertical columns called groups.
4. Elements are classified into s, p, d, and f blocks based on electronic configuration.
29) List five characteristic features of fishes
Solution
1. They are cold-blooded aquatic vertebrates.
2. The body is streamlined and covered with scales.
3. Respiration takes place through gills.
4. They have fins for locomotion.
5. Heart is two-chambered.
30) What are permanent tissues? Describe the different types of simple permanent tissues
Solution
Permanent Tissues: Tissues that have lost the ability to divide and have attained a definite shape, size, and function.
Simple Permanent Tissues:
- Parenchyma: Living cells with thin walls, store food, and provide support.
- Collenchyma: Living cells with thickened corners, provide mechanical support and flexibility.
- Sclerenchyma: Dead cells with thick lignified walls, provide strength and rigidity.
31) a) Why do we sweat?
b) Differentiate Kwarshiorkar from Marasmus
Solution
a) Why do we sweat?
Sweating helps in regulating body temperature. When sweat evaporates from the skin surface, it takes latent heat from the body, causing a cooling effect.
b) Kwarshiorkor vs Marasmus:
| Kwarshiorkor | Marasmus |
|---|
| Caused by Protein deficiency. | Caused by Protein and Energy (Calorie) deficiency. |
| Symptoms: Swollen belly (Pot belly), edema. | Symptoms: Severe wasting of muscles, dry skin, "old man" appearance. |
32) What do you conclude about the speed of light in diamond if the refractive index of diamond is 2.41?
Solution
Refractive Index (\(\mu\)) = Speed of light in vacuum (c) / Speed of light in medium (v)
\(2.41 = \frac{c}{v}\)
\(\Rightarrow v = \frac{c}{2.41}\)
Conclusion: The speed of light in diamond is \(\frac{1}{2.41}\) times the speed of light in vacuum (or air). Light travels very slowly in diamond compared to air.
IV. Answer all questions. (3x7=21)
33) a) How will you find the thickness of a one rupee coin?
(OR)
b) i) Explain the different types of motion? (5)
ii) What are the uses of convex mirror? (2)
Solution
a) Finding thickness of a coin using Screw Gauge:
1. Find the Least Count (LC) and Zero Error (ZE) of the screw gauge.
2. Place the coin between the stud and the spindle.
3. Rotate the ratchet until the coin is held gently.
4. Note the Pitch Scale Reading (PSR) and Head Scale Coincidence (HSC).
5. Calculate Total Reading = PSR + (HSC × LC) ± ZC.
6. Repeat for different positions to get the average thickness.
(OR)
b) i) Types of Motion:
1. Linear Motion: Motion along a straight line.
2. Circular Motion: Motion along a circular path.
3. Oscillatory Motion: To and fro motion about a fixed point.
4. Rotatory Motion: Spinning about an axis.
5. Random Motion: Irregular motion.
ii) Uses of Convex Mirror:
1. Used as rear-view mirrors in vehicles.
2. Used in street lights to spread light over a larger area.
34) a) i) State the Gay Lussac's law of combining volumes. Explain with an illustration. (4)
ii) List down the differences between Ionic and Covalent compounds. (3)
(OR)
b) i) Give the test to identify acids and bases. (3)
ii) Explain Tyndall effect and Brownian movement with suitable diagram (4)
Solution
a) i) Gay Lussac's Law:
When gases react, they do so in volumes which bear a simple ratio to one another, and to the volume of the gaseous product, provided all measurements are made at the same temperature and pressure.
Illustration: \(H_2 + Cl_2 \rightarrow 2HCl\). 1 volume of Hydrogen reacts with 1 volume of Chlorine to produce 2 volumes of HCl (Ratio 1:1:2).
a) ii) Ionic vs Covalent Compounds:
| Ionic Compounds | Covalent Compounds |
|---|
| Formed by transfer of electrons. | Formed by sharing of electrons. |
| High melting and boiling points. | Low melting and boiling points. |
| Conduct electricity in molten/solution state. | Do not conduct electricity (mostly). |
(OR)
b) i) Tests for Acids and Bases:
1.
Litmus Test: Acid turns blue litmus red; Base turns red litmus blue.
2.
Phenolphthalein: Acid - Colourless; Base - Pink.
3.
Methyl Orange: Acid - Red/Pink; Base - Yellow.
b) ii) Tyndall Effect & Brownian Movement:
Tyndall Effect: Scattering of light by colloidal particles making the light path visible.
Brownian Movement: The continuous, random, zig-zag motion of colloidal particles due to bombardment by dispersion medium molecules. (Diagram: Zig-zag lines representing particle path).
35) a) i) Give an account on phylum Arthropoda? (3)
ii) Give the difference between Mitosis and Meiosis. (4)
(OR)
b) i) Write about the elements of Xylem? (4)
ii) Explain the role of food control agencies in India. (3)
Solution
a) i) Phylum Arthropoda:
1. Largest phylum in animal kingdom.
2. They have jointed appendages (legs).
3. Body is segmented into head, thorax, and abdomen.
4. Exoskeleton made of chitin.
5. Example: Prawn, Cockroach, Butterfly.
a) ii) Mitosis vs Meiosis:
| Mitosis | Meiosis |
|---|
| Occurs in somatic (body) cells. | Occurs in reproductive (germ) cells. |
| Produces 2 daughter cells. | Produces 4 daughter cells. |
| Chromosome number remains same (2n). | Chromosome number is halved (n). |
| Used for growth and repair. | Used for gamete formation. |
(OR)
b) i) Elements of Xylem:
1.
Tracheids: Elongated, dead cells with tapering ends; conduct water.
2.
Vessels (Tracheae): Long tube-like structures; main water-conducting elements.
3.
Xylem Parenchyma: Living cells; store food.
4.
Xylem Fibres: Dead sclerenchyma fibres; provide mechanical support.
b) ii) Food Control Agencies in India:
1.
FSSAI (Food Safety and Standards Authority of India): Regulates food manufacture, storage, and distribution to ensure safety.
2.
ISI (Indian Standards Institute): Certifies industrial products like electrical appliances, etc. (Now BIS).
3.
AGMARK: Certifies agricultural products (oil, pulses, honey) for quality.
4.
FPO (Fruit Process Order): Certifies fruit products like jams and pickles.
