Q. 1. (A) Choose the correct alternative.
(i) In modern periodic table the non-metals are found in ....................... .
Answer: (B) p-block
(ii) \( CuSO_{4(aq)} + Zn_{(s)} \longrightarrow ZnSO_{4(aq)} + Cu_{(s)} \)
This is .................. type of chemical reaction.
This is .................. type of chemical reaction.
Answer: (A) displacement
(iii) The unit of electric power is ................... .
Answer: (C) Watt
(iv) We can see the sun even when it is little below the horizon because of ........................ .
Answer: (B) refraction of light
(v) ................................... is one of the combustible component of L.P.G.
Answer: (B) Propane
Q. 1. (B) Answer the following questions.
(i) Write the correlation:
Brass : Copper and Zinc : : Bronze : ..................
Brass : Copper and Zinc : : Bronze : ..................
Answer: Copper and Tin
(ii) Write True or False:
Benzene is an aromatic compound.
Benzene is an aromatic compound.
Answer: True
(iii) Find the odd one out:
Myopia; Presbyopia; Hypermetropia; Retina
Myopia; Presbyopia; Hypermetropia; Retina
Answer: Retina (Reason: It is a part of the human eye, while others are defects of vision).
(iv) What is angle of refraction when angle of incidence is 0° ?
Answer: 0° (The light ray passes undeviated).
(v) Name two appliances which work on the principle of magnetic effect of electric current.
Answer: Electric Bell, Electric Motor (or Loudspeaker).
Q. 2. (A) Give scientific reasons (any two).
(i) Sodium is always kept in kerosene.
Reason: Sodium is a highly reactive metal. It reacts vigorously with atmospheric oxygen and moisture even at room temperature and can catch fire easily. To prevent this reaction and accidental fire, sodium is kept immersed in kerosene, as it does not react with kerosene and sinks in it.
(ii) A simple microscope is used for watch repairs.
Reason: A simple microscope consists of a convex lens of short focal length. When an object is placed within its focal length, it produces a virtual, erect, and magnified image. Watch repairers need to see the minute and intricate parts of a watch clearly to repair them, which is achieved by using a simple microscope.
(iii) It is necessary to manage the space debris.
Reason: Space debris consists of non-functional satellites, launcher parts, and other fragments revolving around the Earth at high speeds. This debris poses a threat of collision with operational satellites, space stations, and spacecraft. Such collisions can generate even more debris (Kessler syndrome), potentially rendering certain orbits unusable for future space missions. Therefore, it is essential to manage space debris.
Q. 2. (B) Answer the following questions (any three).
(i) The absolute refractive index of water is 1.33. What is the velocity of light in water?
(Velocity of light in vacuum = \( 3 \times 10^8 \) m/s)
(Velocity of light in vacuum = \( 3 \times 10^8 \) m/s)
Solution:
Given:
Refractive index of water (\( n \)) = 1.33
Velocity of light in vacuum (\( v_1 \)) = \( 3 \times 10^8 \) m/s
To find: Velocity of light in water (\( v_2 \))
Formula: \( n = \frac{v_1}{v_2} \)
Calculation:
\( 1.33 = \frac{3 \times 10^8}{v_2} \)
\( v_2 = \frac{3 \times 10^8}{1.33} \)
\( v_2 \approx 2.255 \times 10^8 \) m/s
Answer: The velocity of light in water is approximately \( 2.26 \times 10^8 \) m/s.
Given:
Refractive index of water (\( n \)) = 1.33
Velocity of light in vacuum (\( v_1 \)) = \( 3 \times 10^8 \) m/s
To find: Velocity of light in water (\( v_2 \))
Formula: \( n = \frac{v_1}{v_2} \)
Calculation:
\( 1.33 = \frac{3 \times 10^8}{v_2} \)
\( v_2 = \frac{3 \times 10^8}{1.33} \)
\( v_2 \approx 2.255 \times 10^8 \) m/s
Answer: The velocity of light in water is approximately \( 2.26 \times 10^8 \) m/s.
(ii) Observe the figure (Ice slab with wire and weights) and answer the questions given below.
(a) Name the phenomenon shown in the figure.
(b) Define the above phenomenon.
(a) Name the phenomenon shown in the figure.
(b) Define the above phenomenon.
(a) The phenomenon is Regelation.
(b) The phenomenon in which ice converts to liquid due to applied pressure and then reconverts to ice once the pressure is removed is called regelation.
(b) The phenomenon in which ice converts to liquid due to applied pressure and then reconverts to ice once the pressure is removed is called regelation.
(iii) \( 2H_2S + SO_2 \longrightarrow 3S \downarrow + 2H_2O \)
(a) Identify the above chemical reaction.
(b) Name the type of reaction in A and B (referring to oxidation/reduction arrows).
(a) Identify the above chemical reaction.
(b) Name the type of reaction in A and B (referring to oxidation/reduction arrows).
(a) It is a Redox Reaction.
(b)
Reaction A (involving \( H_2S \rightarrow S \)): Oxidation (Loss of Hydrogen).
Reaction B (involving \( SO_2 \rightarrow S \)): Reduction (Loss of Oxygen).
(b)
Reaction A (involving \( H_2S \rightarrow S \)): Oxidation (Loss of Hydrogen).
Reaction B (involving \( SO_2 \rightarrow S \)): Reduction (Loss of Oxygen).
(iv) Rearrange the column 2 and 3 so as to match with the column 1.
| Column 1 | Column 2 (Corrected) | Column 3 (Corrected) |
|---|---|---|
| (1) Triad | Average of the atomic masses of first and third element | Dobereiner |
| (2) Octave | Properties of the eighth element are similar to first | Newlands |
(v) Define the following terms:
(a) Escape velocity
(b) Free fall
(a) Escape velocity
(b) Free fall
(a) Escape velocity: The minimum initial velocity needed by an object projected from the surface of a celestial body (like Earth) to overcome its gravitational pull and escape into space is called escape velocity.
(b) Free fall: The motion of a body under the influence of gravity alone is called free fall.
(b) Free fall: The motion of a body under the influence of gravity alone is called free fall.
Q. 3. Answer the following questions (any five).
(i) What information will you get from the given reaction?
\( CaCO_{3(s)} \xrightarrow{\Delta} CaO_{(s)} + CO_2 \uparrow \)
\( CaCO_{3(s)} \xrightarrow{\Delta} CaO_{(s)} + CO_2 \uparrow \)
1. This is a Decomposition Reaction, where a single reactant breaks down into simpler products.
2. It is an Endothermic Reaction, indicated by the delta symbol (\(\Delta\)), meaning heat is absorbed for the reaction to occur.
3. Solid Calcium Carbonate (Limestone) decomposes into solid Calcium Oxide (Quick lime) and Carbon Dioxide gas evolves.
2. It is an Endothermic Reaction, indicated by the delta symbol (\(\Delta\)), meaning heat is absorbed for the reaction to occur.
3. Solid Calcium Carbonate (Limestone) decomposes into solid Calcium Oxide (Quick lime) and Carbon Dioxide gas evolves.
(ii) Observe the following ray diagram (Compound Microscope) and answer the questions:
(a) Identify the instrument shown in the diagram.
(b) What is the combined effect of two lenses?
(c) Write the use of the above instrument.
(a) Identify the instrument shown in the diagram.
(b) What is the combined effect of two lenses?
(c) Write the use of the above instrument.
(a) Instrument: Compound Microscope.
(b) Combined Effect: The two convex lenses (objective and eyepiece) work together to produce a highly magnified, virtual, and inverted image of a tiny object.
(c) Use: It is used to observe minute objects like blood cells, bacteria, and plant/animal cells which cannot be seen with the naked eye.
(b) Combined Effect: The two convex lenses (objective and eyepiece) work together to produce a highly magnified, virtual, and inverted image of a tiny object.
(c) Use: It is used to observe minute objects like blood cells, bacteria, and plant/animal cells which cannot be seen with the naked eye.
(iii) Read the following paragraph about Rainbows and answer:
(a) Which three major phenomena are responsible for rainbow formation?
(b) How does refraction take place?
(c) Draw a diagrammatic representation of rainbow production.
(a) Which three major phenomena are responsible for rainbow formation?
(b) How does refraction take place?
(c) Draw a diagrammatic representation of rainbow production.
(a) The three major phenomena are Dispersion, Refraction, and Total Internal Reflection of light.
(b) Refraction takes place twice: first when sunlight enters the water droplet from the air (bending towards the normal and dispersing), and second when the light leaves the droplet into the air (bending away from the normal).
(c) Diagram Description: A water droplet is shown. A white light ray enters, splits into colors (dispersion), reflects internally at the back surface of the droplet, and finally refracts out as a spectrum (VIBGYOR).
(b) Refraction takes place twice: first when sunlight enters the water droplet from the air (bending towards the normal and dispersing), and second when the light leaves the droplet into the air (bending away from the normal).
(c) Diagram Description: A water droplet is shown. A white light ray enters, splits into colors (dispersion), reflects internally at the back surface of the droplet, and finally refracts out as a spectrum (VIBGYOR).
(iv) From the elements of second period (Li, Be, B, C, N, O, F, Ne):
(a) Name the elements in which both the shells are completely filled with electrons.
(b) Name the element which has same number of electrons in both the shells.
(c) Which is the most electropositive element in this period?
(a) Name the elements in which both the shells are completely filled with electrons.
(b) Name the element which has same number of electrons in both the shells.
(c) Which is the most electropositive element in this period?
(a) Neon (Ne) (Atomic number 10; Configuration: 2, 8). Both K and L shells are filled.
(b) Beryllium (Be) (Atomic number 4; Configuration: 2, 2). It has 2 electrons in both K and L shells.
(c) Lithium (Li) is the most electropositive element in this period (Electropositivity decreases from left to right).
(b) Beryllium (Be) (Atomic number 4; Configuration: 2, 2). It has 2 electrons in both K and L shells.
(c) Lithium (Li) is the most electropositive element in this period (Electropositivity decreases from left to right).
(v) Explain on which factor the value of acceleration due to gravity ‘g’ depends.
The value of 'g' depends on:
- Shape of the Earth (Latitude): The Earth is not a perfect sphere; it is flattened at the poles and bulged at the equator. 'g' is highest at the poles (where radius is minimum) and lowest at the equator (where radius is maximum).
- Height (Altitude): As the height above the Earth's surface increases, the value of 'g' decreases.
- Depth: As we go deep inside the Earth, the effective mass responsible for gravity decreases, so the value of 'g' decreases.
(vi) Explain the following terms:
(a) Metallurgy
(b) Ores
(c) Gangue
(a) Metallurgy
(b) Ores
(c) Gangue
(a) Metallurgy: The science and technology regarding the extraction of metals from their ores and their purification for various uses is called metallurgy.
(b) Ores: The minerals from which metals can be separated economically and profitably are called ores.
(c) Gangue: The impurities such as soil, sand, rocky material, etc., present along with the metal compounds in the ore are called gangue.
(b) Ores: The minerals from which metals can be separated economically and profitably are called ores.
(c) Gangue: The impurities such as soil, sand, rocky material, etc., present along with the metal compounds in the ore are called gangue.
(vii) Give the names of the following satellite series developed by India:
(a) Telecom/TV/Meteorological services.
(b) Education.
(c) Navigation/Location.
(a) Telecom/TV/Meteorological services.
(b) Education.
(c) Navigation/Location.
(a) INSAT (Indian National Satellite) and GSAT series.
(b) EDUSAT (GSAT-3).
(c) IRNSS (Indian Regional Navigation Satellite System) or NavIC.
(b) EDUSAT (GSAT-3).
(c) IRNSS (Indian Regional Navigation Satellite System) or NavIC.
(viii) (a) What is meant by anomalous behaviour of water?
(b) Explain its role in preserving aquatic life in cold climate.
(b) Explain its role in preserving aquatic life in cold climate.
(a) Generally, liquids expand on heating and contract on cooling. However, water shows a special behavior. Between 0°C and 4°C, water contracts on heating and expands on cooling. This unique property is called the anomalous behavior of water.
(b) In cold regions, when the atmospheric temperature drops, the surface water cools and contracts, becoming denser. It sinks to the bottom. This process continues until the water reaches 4°C (maximum density). If the temperature drops further (below 4°C), the surface water expands, becomes lighter, and stays on top, eventually freezing into ice at 0°C. Ice acts as an insulator, preventing heat loss from the water below. Thus, the water beneath the ice remains at 4°C, allowing aquatic life to survive.
(b) In cold regions, when the atmospheric temperature drops, the surface water cools and contracts, becoming denser. It sinks to the bottom. This process continues until the water reaches 4°C (maximum density). If the temperature drops further (below 4°C), the surface water expands, becomes lighter, and stays on top, eventually freezing into ice at 0°C. Ice acts as an insulator, preventing heat loss from the water below. Thus, the water beneath the ice remains at 4°C, allowing aquatic life to survive.
Q. 4. Answer the following question (any one).
(i) Observe the diagram (Electric Motor) and answer:
(a) Identify the above diagram.
(b) Write the principle on which the above appliance works.
(c) Write the working of the above appliance.
(d) Write the use of the above appliance.
(a) Identify the above diagram.
(b) Write the principle on which the above appliance works.
(c) Write the working of the above appliance.
(d) Write the use of the above appliance.
(a) Identification: Electric Motor.
(b) Principle: A current-carrying conductor placed in a magnetic field experiences a force (Fleming's Left Hand Rule).
(c) Working: When current flows through the rectangular coil (ABCD) placed between the magnets, magnetic forces act on arms AB and CD in opposite directions (one up, one down). This creates a torque that rotates the coil. The split ring commutator reverses the direction of current in the coil every half rotation, ensuring the torque continues in the same direction, resulting in continuous rotation.
(d) Use: Used in electric fans, mixers, washing machines, computers, etc.
(b) Principle: A current-carrying conductor placed in a magnetic field experiences a force (Fleming's Left Hand Rule).
(c) Working: When current flows through the rectangular coil (ABCD) placed between the magnets, magnetic forces act on arms AB and CD in opposite directions (one up, one down). This creates a torque that rotates the coil. The split ring commutator reverses the direction of current in the coil every half rotation, ensuring the torque continues in the same direction, resulting in continuous rotation.
(d) Use: Used in electric fans, mixers, washing machines, computers, etc.
(ii) Read the paragraph on Hydrocarbons and answer:
(a) What is meant by hydrocarbon?
(b) Name the smallest hydrocarbon.
(c) Define unsaturated compound.
(d) Differentiate between Alkene and Alkyne.
(a) What is meant by hydrocarbon?
(b) Name the smallest hydrocarbon.
(c) Define unsaturated compound.
(d) Differentiate between Alkene and Alkyne.
(a) Hydrocarbon: The organic compounds which contain carbon and hydrogen as the only two elements are called hydrocarbons.
(b) Smallest Hydrocarbon: Methane (\( CH_4 \)).
(c) Unsaturated Compound: Carbon compounds having a double bond or triple bond between two carbon atoms are called unsaturated compounds.
(d) Difference between Alkene and Alkyne:
(b) Smallest Hydrocarbon: Methane (\( CH_4 \)).
(c) Unsaturated Compound: Carbon compounds having a double bond or triple bond between two carbon atoms are called unsaturated compounds.
(d) Difference between Alkene and Alkyne:
- Alkene: Unsaturated hydrocarbons containing at least one carbon-carbon double bond (\( C=C \)). General formula: \( C_n H_{2n} \).
- Alkyne: Unsaturated hydrocarbons containing at least one carbon-carbon triple bond (\( C \equiv C \)). General formula: \( C_n H_{2n-2} \).
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