Check the solutions of JKSCERT Class 8th Science Paper 2023-24. The solutions have been prepared in simple and concise language to suit my children at Govt. schools
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| JKSCERT Class 8th Solved Science paper 2023-24; Mufawad |
Section A:
(Multiple Choice Questions)
a. Richter Scale b. Beauford Scale c. Fujita Scale d. Mercalli Intensity Scale
Ans: a. Richter Scale
2. What is Crop Rotation?
a. Planting the same crop in the same field year after year
b. Alternating different crops in the same field over several seasons
c. Growing crops in rotation with animal grazing
d. Introducing genetically modified crops to enhance yield
Ans: b. Alternating different crops in the same field over several seasons
3. What is Static Friction?
a. Friction between two surfaces in motion
b. Friction between two surfaces in rest
c. Friction between a moving object and the air
d. Friction between a stationary object and a fluid
Ans: b. Friction between two surfaces in rest
4. What is the general term for the reaction of metal with oxygen?
a. Oxidation b. Reduction c. Precipitation d. Sublimation
Ans: a. Oxidation
5. What is the process called when an electric current passes through an electrolyte and causes a chemical reaction?
a. Electroplating b. Electrolysis c. Electromagnetism d. Electrocution
Ans: b. Electrolysis
6. Which of the following is not a common type of friendly microbe?
a. Bacteria b. Fungi c. Virus d. Yeast
Ans: c. Virus
7. Which of the following methods of food preservation involves removing moisture from the food?
a. Canning b. Freezing c. Dehydration d. Pickling
Ans: c. Dehydration
(Case Based Questions/ Passage)
Metals and Nonmetals are two distinct categories of elements found in the periodic table. Each group possesses unique properties and characteristics that differentiate them from one another. Understanding these properties is essential in various fields, including chemistry, material sciences, and engineering.
Metals are typically solid substances that have lustrous appearance and good conductors of heat and electricity. They often exhibit high densities and melting points, making them useful in various industrial applications. Metals can further be categorized into alkali metals, alkaline earth metals, transition metals and inner transition metals, each with its own set o0f properties and applications.
On the other hand, nonmetals are elements that lack the typical characteristics of metals. They can exist in various states of matter, including solids, liquids and gases. Non metals are generally poor conductors of heat and electricity and they often have low densities and melting points compared to metals. Examples of nonmetals include Carbon, Sulphur, Nitrogen and Oxygen, which play crucial role in biological processes and environmental systems.
Understanding the properties of metals and nonmetals allows scientists and engineers to design and develop innovative materials for a wide range of applications. From building structures and electrical devices to manufacturing chemicals and pharmaceuticals, the properties of these elements shape the world around us.
8. Which of the following is NOT the characteristic of metals?
a. Good conductors of Heat and Electricity b. Low Densities
c. Lustrous appearance d. High Melting points
Ans: b. Low Densities
9. Which is one common characteristic of Non-Metals?
a. High densities b. Good conductors of heat and electricity
c. Lustrous d. Poor conductors of heat and electricity
Ans: d. Poor conductors of heat and electricity
10. How are metals and nonmetals typically distinguished based on their conductive properties?
a. Metals are good conductors, while nonmetals are poor conductors
b. Non metals are good conductors, while metals are poor conductors
c. Both are equally good conductors
d. Both are equally poor conductors
Ans: a. Metals are good conductors, while nonmetals are poor conductors
(Assertion-Reason Type Questions)
A. Both A and R are True and R is the correct explanation of A
B. Both A and R are True and R is not the correct explanation of A
C. A is True and R is False
D. A is False and R is True
11. Assertion (A): Friction always opposes the relative motion between two surfaces in contact
Reason (R): Friction arises due to the irregularities present on the surfaces in contact, which resist motion by generating heat
Ans: B. Both A and R are True and R is not the correct explanation of A
12. Assertion (A): Crop rotation is an effective agricultural practice for maintaining soil fertility and reducing the risk of pest infestation
Reason (R): Crop rotation involves planting the same crop in the same field year after year, ensuring consistent yields and minimizing the need of chemical fertilizers and pesticides
Ans: C. A is True and R is False
13. Assertion (A): Microorganisms play crucial role in various ecological processes and industries
Reason (R): Some micro-organisms contribute to nutrient cycling, soil fertility and the production of foods like yogurt and cheese, while others can cause infections and diseases in humans and animals
Ans: A. Both A and R are True and R is the correct explanation of A
Section B
(Very Short Answer Type Questions)
Ans: Two human activities that contribute significantly to global warming are use of fossil fuels and deforestation.
Both the activities can rise on green house gases such as CO2, CO, CH4 etc. This causes climate change.
15. Name two solid lubricants and state where they are used?
Ans: Name of the two solid lubricants are Graphite and Talcum powder.
Graphite is used in the machines where as talcum powder is used on carrom boards.
16. What changes occur in Males and Females at Puberty?
Ans: The changes that occur in males and females at Puberty are as follows:
a. Increase in height and weight.
b. Growth of hair on different body parts.
c. Maturation of sex organs resulting in production of eggs and sperms.
d. Broadening of shoulders and chest in boys and waist in girls.
e. Acne and pimples
f. change in voice.
17. What are the different methods of Sowing?
Ans: There are many methods of sowing such as broadcasting, using seed drills etc.
18. What are the different stages in the development of embryo?
Ans: The different stages in the development of embryo are:
i. Fusion of sperm with egg
ii. Formation of Zygote
iii. Formation of Embryo
iv. Formation of Foetus
19. Elaborate in brief the process of Pasteurization?
Ans: During pasteurization, Milk is heated at 700c for 15 to 30 seconds and then quickly chilled.
Pasteurization stops the growth of bacteria.
Section C
(Short Answer Type Questions)
Ans: When any unwanted substance enters the water, It is called Water pollution. There are different reasons for the pollution of water such as:
i. Releasing sewage into water
ii. Releasing industrial pollutants into water
iii. Releasing water from agriculture fields into water
iv. Throwing garbage into water
21. What is an Electroscope? Explain in brief
Ans: Electroscope is an instrument used to detect charge on the body.
It contains a metal rod inside a bottle. On one side of metal rod, two Aluminium strips are attached.
When one side of metal rod is touched by charged body, the aluminium strips move away from each other.
22. What are endocrine glands and name the hormones secreted by these endocrine glands?
Ans: Endocrine glands are those glands which release their secretions directly into the blood stream.
The hormones secreted by Endocrine glands are as follows:
|
Gland |
Hormone |
|
Thyroid |
Thyroxine |
|
Pancreases |
Insulin |
|
Adrenal Gland |
Adrenaline |
|
Ovaries |
Estrogen |
|
Testes |
Testosterone |
23. Draw a simple circuit showing the process of Electroplating and explain in brief.
Ans: The process of depositing a layer of metal over another metal with the help of electricity is called Electroplating.
Explanation: During electroplating, copper plates are taken as electrodes and copper sulphate is taken as electrolyte.
When the current is passed through the solution, Copper sulphate breaks into Copper+ and Sulphate-, The copper gets deposited at the Cathode.
24. Explain in brief the stages in the Life Cycle of Frog.
Ans: Frogs undergo metamorphosis. Theirs life cycle has 3 stages:
Stage I: Egg: Frogs lay eggs in the water. They undergo external fertilization
Stage II: Tadpole: It stays in the water. It has gills.
Stage III: Adult Frog: It shape is different from the tadpole and can live both on land and water.
Section D
(Long Answer Type Questions)
Ans: 1. Regular reflection occurs on plane polished surfaces whereas diffused reflection occurs on uneven surfaces
2. Regular reflection follows laws of reflection, Diffused reflection does not follow laws of reflection.
The laws of reflection are valid on plain polished surfaces, The diffused reflection occurs on such surfaces which are not polished. Hence it is not failure of laws of reflection.
25 (Or) Describe the construction of Kaleidoscope?
Ans: Take three rectangular mirror strips, join them together in the shape of prism.
Put it in circular cardboard tube. The tube should be longer than the mirror strips.
Close one end of the tube by disc having a hole in the centre.
At the other end, touching the mirrors, fix a circular glass plate.
Put pieces of coloured bangles inside it.
Thus our kaleidoscope is formed.
26. Draw a well labelled diagram with explanation of the parts of a Plant Cell.
Ans:
The parts of a Plant cell include:
Cell wall: It provides strength to the cell
Cell membrane: It lies inside the cell wall
Nucleus: It controls the cell
Chloroplasts: It helps in the photosynthesis
Mitochondria: It produce energy for the cell.
Endoplasmic Reticulum: It helps to make proteins and lipids.
26 (Or) What are the different types of cell organelles and what is their function.
Ans: The different cell organelles and their functions are:
I. Mitochondria: It is powerhouse of cell and provides energy to cell in form of ATP.
II. Chloroplasts: It contains chlorophyll and helps plants to make own food.
III. Endoplasmic reticulum: It helps to make proteins and lipids.
IV. Golgi complex: It collects and distributes the substances inside and out of cell.
IV. Lysosomes: It breaks down various materials inside the cell.
26 (Or) What are the different types of cell organelles and what is their function.
Ans: The different cell organelles and their functions are:
I. Mitochondria: It is powerhouse of cell and provides energy to cell in form of ATP.
II. Chloroplasts: It contains chlorophyll and helps plants to make own food.
III. Endoplasmic reticulum: It helps to make proteins and lipids.
IV. Golgi complex: It collects and distributes the substances inside and out of cell.
IV. Lysosomes: It breaks down various materials inside the cell.
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