Explanation

Differentiate between network and internet.

Network: A network is a group of interconnected computers or devices that can share resources and information, typically within a local area (LAN) or wide area (WAN).

Internet: The internet is a global network of networks that connects millions of private, public, academic, and governmental systems, enabling worldwide communication and information sharing.

Explanation

Ahmad stands at point D, 2m in front of a spotlight at point A. He is 1.6m tall and is facing the wall of a building which is 10.5m away from him. How tall (BC) is his shadow on the wall of the building (5 marks)

To find the height $BC$ of Ahmad's shadow on the wall of the building, we can use the properties of similar triangles.

Given:

1. Ahmad's height $DE = 1.6$ m.
2. Distance from the spotlight at $A$ to Ahmad at $D$is $2$ m.
3. Distance from Ahmad at $D$ to the wall at $B$ is $10.5$ m.
4. Total distance $AB = 2 + 10.5 = 12.5$m.

Using similar triangles:

$$$$BCAB=DEAD​

Substitute the values:

$$frac{BC}{12.5} = frac{1.6}{2}$$ $$BC = 12.5 times frac{1.6}{2} = 12.5 times 0.8 = 10 text{ m}$$

Height $BC = 10$ m.

Explanation

Question: A telephone company charges initially Rs.0.50 and then Rs. 0.11 for every minute. Write an expression that gives the cost of a call that lasts N minutes. (5 marks)

I apple - 2 Rs

8 apples = 2x8

= 16 Rs

Initial charges = Rs 0.5-

Next every min charge = RS0.11 Rs 

No. minutes charges = Nx0.1 =0.11N.R

Total charge = (0.50 +0.11N) Rs

Explanation

Explanation

The perimeter of the rectangle given below is 114 cm. Find the area of the rectangle. (5 marks)

Explanation

(b) How the carbohydrates, proteins, and fats are digested in humans? (5)

Carbohydrates:
Carbohydrates are broken down into glucose by enzymes like amylase in the mouth and small intestine.

Proteins:
Proteins are broken down into amino acids by pepsin in the stomach and proteases in the small intestine.

Fats:
Fats are emulsified by bile and then broken down into fatty acids and glycerol by lipase in the small intestine.

Explanation

Question:

 What are antioxidants and why are they used in foods? Write a short note on natural and synthetic antioxidants. (5 amrks)

Antioxidants:
Antioxidants are compounds that prevent oxidative damage in cells, thus extending the shelf life and quality of foods.

Natural vs. Synthetic:
Natural antioxidants (e.g., vitamin C, E) are derived from plants, while synthetic ones (e.g., BHA, BHT) are lab-made; both help preserve food freshness but vary in sources and stability.

Explanation

NOTE: The question has 4 parts each part of the question contains 5 marks

Question: (a) What is the difference between fog and smog? What are the causes of smog and its effects on human health? Write a short note on one of the latest technologies to eliminate smog and avoid atmospheric pollution. (5)

Difference between Fog and Smog:
Fog is a natural weather phenomenon caused by condensed water vapor, while smog is a type of air pollution formed from pollutants, mainly from vehicles and industry.

Causes of Smog:
Smog is caused by emissions from vehicles, factories,

Effects on Human Health:
Smog can cause respiratory issues, eye irritation

Latest Technology to Eliminate Smog:
Photocatalytic materials, such as titanium dioxide coatings

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(b)What is the role of oxygen-demanding wastes in water pollution? How it can be prevented? (5)

Role in Water Pollution:
Oxygen-demanding wastes, like organic matter from sewage, agricultural runoff, and industrial discharge, consume oxygen in water as they decompose.

Reducing pollution sources by treating wastewater, promoting sustainable agriculture

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(c)What is the biosphere? Write a note on the ‘Energy Resources’ available in the biosphere. (5)

The biosphere is the global ecological system that includes all living organisms and their interactions with the Earth's atmosphere, land, and water. Energy resources in the biosphere include solar energy, wind, water, and biomass, which are vital for sustaining life and ecosystems.

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(d)What are the different layers of the atmosphere? On what basis these layers are classified? In which layer ‘Auroras’ are formed and where do satellites orbit? (5)

The atmosphere consists of five layers: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere, classified based on temperature gradients and altitude.

Auroras form in the thermosphere, while satellites typically orbit in the exosphere.

Explanation

Q. 3. (a) (i) Why are the bat and whale considered mammals?

Bats and whales are considered mammals because they share several characteristics, including:

Warm-blooded: 

Mammary glands:

Live birth: 

Complex brains: 

Backbone: 

(ii) Write a note on liver juice ‘Bile’. (5)

(b)How the urine is formed? Describe the role of the kidney in excretion. (5)

Urine Formation:
Urine is formed through three main processes in the kidneys: filtration, reabsorption, and secretion.

Blood is filtered in the glomerulus, removing waste and excess substances, which pass into the tubules.

Role of Kidney in Excretion:
The kidneys filter waste, excess ions, and toxins from the blood to produce urine, which is then excreted. 

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(c) (i) How is a bacterial cell different from a plant cell?

Bacterial Cell vs. Plant Cell:
A bacterial cell is a prokaryote, meaning it lacks a defined nucleus and membrane-bound organelles, while a plant cell is a eukaryote with both a nucleus and organelles.

Plant cells have a rigid cell wall made of cellulose and contain chloroplasts for photosynthesis, whereas bacterial cell walls contain peptidoglycan, and bacteria lack chloroplasts.

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(ii) What do you think low temperatures slow down cold-blooded animals? (5)

Low temperatures slow down cold-blooded animals because their body temperature depends on the external environment.

As temperatures drop, their metabolic processes, which control energy and movement, slow significantly, causing them to become less active or even enter a dormant state. This helps them conserve energy until temperatures rise.

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(d)What is hepatitis, its types, causes, prevention, and cure? (5)

Hepatitis:
Hepatitis is an inflammation of the liver, commonly caused by viral infections, but it can also result from toxins, alcohol, or autoimmune diseases.

Types:
The main types are Hepatitis A, B, C, D, and E, differing in transmission modes, severity, and long-term effects.

Prevention and Cure:
Vaccines (for Hepatitis A and B), practicing good hygiene, safe food, and water consumption prevent hepatitis; treatment varies by type, including antiviral medications and lifestyle changes for management.

Explanation

NOTE: The question has 4 parts each part of the question contains 5 marks

(part a) Define ceramic and nano-ceramic materials. Why the nano-ceramics show better properties than their ceramic counterparts? Write the applications of ceramic materials.

(part b)What is ‘Black Hole’? How black holes are formed and discovered? (5)

Black Hole:
A black hole is a region in space with a gravitational pull so strong that nothing, not even light, can escape from it.

Formation and Discovery:
 They were first theorized by Albert Einstein's general theory of relativity a

(part c)Write two applications of each of the following electromagnetic radiations:

(i) Ultraviolet: 1. Sterilization: 2. Tanning: 

(ii) Infra-red: 1. Thermal Imaging: 2. Heating:

(iii) Microwaves: 1. Cooking: 2. Satellite Communication:

(iv) Radio waves 1. Broadcasting: 2. Wireless Communication:

(v) X-rays. 1. Medical Imaging: 2. Security:

(part d)What is Wildfire? Explain its types, causes, spread, and preventions. 

Wildfire:
A wildfire is an uncontrolled fire that spreads rapidly across vegetation, often in forested areas, fueled by dry conditions, strong winds, and flammable materials.

Types of Wildfire:

1. Ground Fires: 
2. Surface Fires: 
3. Crown Fires: 

Causes of Wildfire:
Wildfires are caused by natural factors like lightning and human activities such as unattended campfires, discarded cigarettes, or arson.

Wildfires spread 

Preventions of Wildfire: