SEE, PABSON, NPABSON Questions and Answer: Science

NATIONAL PABSAN
Pre-Board Examination-2081
Science & Technology
Time: 3hrs

All the question are compulsory

Tick the correct alternatives.

[Group-Al

Multiple choice questions. [1x10=10]

1- Which of the following is the negative impact of digital technology?

(a) Digital library (b) cyber bullying

2- Which is not gymnosperm?

(a) Cycas (b) Pine

3-Chlorophyll is absent in.

(a) mushroom (b) moss

4- Why is cycas kept in gymnosperm?

(a) It bears flowers and produces seed. (b) It bears flowers and has pointed leaf.

5-Which is the value of acceleration due to gravity of the earth zero?

a) At the centre (b) at the sea level

6-On Which principle is a lactometer based?

(a) Pascal's law (b) Archimedes principle

7-Which of the following is the refractive index of water?

(a) 1.36 (b) 1.33

8-Which in the most realistic theory about origin of the universe?

(a) Heliocentric theory (b) Geocentric theory

9- What is denoted by x in the given reaction?

2KClO3 ----- Xà2Kcl +302

(a) catalyst (b) Heat

10. What is the main use of detergent?

(a) taking bath (b) Washing clothes

Answers

1. (b) Cyber bullying 2. (c) Coconut 3. (a) Mushroom 4.(d) It has cone instead of flower and seed is naked.

5. (a) At the centre 6. (b) Archimedes' principle 7. (b) 1.33 8.(d) Big Bang 9. (b) Heat 10. (b) Washing clothes

2-very short answer type questions.

(a) Define independent variables.
Independent variables are the variables that are deliberately changed or controlled in an experiment to observe their effect on dependent variables.

(b) State Pascal's law.
Pascal’s law states that the pressure applied to a confined fluid is transmitted undiminished in all directions throughout the fluid.

(c) Anu cannot distinguish red and green color. What is the main cause of this problem?
The main cause of this problem is color blindness, which occurs due to the absence or defect of red or green cone cells in the retina.

(d) Define power of a lens.
The power of a lens is the ability of the lens to converge or diverge light. It is measured in diopters (D) and is given by: Power (P) =

i.e. P =

(e) Define magnetic flux.
Magnetic flux is the total number of magnetic field lines passing through a given surface.

(g) Write the main ore of iron.
The main ore of iron is Hematite (Fe₂O₃).

(h) Define roasting.
Roasting is the process of heating sulfide ores in the presence of excess air to convert them into oxides. Example: 2ZnS+3O₂→2ZnO +2SO₂

(i) Write a difference between saturated and unsaturated hydrocarbons on the basis of reactivity.
Saturated hydrocarbons (alkanes) are less reactive because they contain only single bonds.
Unsaturated hydrocarbons (alkenes and alkynes) are more reactive due to the presence of double or triple bonds, which can undergo addition reactions.

[Group-c]

3. Why do we use the unit-wise analysis of the equation? Write two reasons.

We use unit wise analysis of the equation:

To verify the correctness of a given equation.
To ensure dimensional consistency in physical equations.

4. Write any 2 characteristics of class Amphibia.

Two characteristics of class Amphibia are:

They can live both in water and on land (dual habitat).
They have moist, glandular skin without scales.

5. Write any 2 differences between drone bee and worker bee.

Drone Bee	Worker Bee
Male bee, developed from unfertilized egg.	Female bee, developed from fertilized egg.
Its main role is mating with the queen.	Performs various tasks like collecting nectar, making honey, and protecting the hive.

6. Write down the major function of DNA and RNA.

The major function of DNA and RNA are mentioned below:

DNA (Deoxyribonucleic Acid): Stores and transmits genetic information.
RNA (Ribonucleic Acid): Helps in protein synthesis by translating genetic codes from DNA.

7. Why did Mendel select the pea plant for his experiment? Give two reasons.

Mendel select the pea plant for his experiment because of the following reasons:

Short life cycle – It grows and reproduces quickly.
Distinct traits – Pea plants have easily distinguishable characteristics like flower color and seed shape.

8. Write any 2 causes of increasing uric acid.

Two causes of increasing uric acid are:

Excessive consumption of protein-rich foods (e.g., red meat, seafood).
Reduced kidney function, leading to poor excretion of uric acid.

9. Many important plants are being extinct in Nepal due to climate change. What role can you play to protect such plants?

Roles I can play to protect important plants from being extinction due to climate change are:

Promote afforestation and reforestation by planting native species.
Spread awareness about climate change and conservation practices.

10. Write any two effects of gravity.

Two effects of gravity are:

It keeps planets in their orbits around the sun.
It causes objects to fall towards the earth.

11. Clarify the statement, "Acceleration due to gravity of the earth is 9.8 m/s²."

This means that when an object falls freely under gravity, its velocity increases by 9.8 m/s every second.

12. Write any two differences between step-up and step-down transformers.

Step-Up Transformer	Step-Down Transformer
Increases voltage	Decreases voltage
Has more turns in the secondary coil than in the primary coil	Has more turns in the primary coil than in the secondary coil

13. Draw a simple diagram of an electromagnet.

14. How does heat enhance the rate of chemical reaction? Give reason.

Heat increases the kinetic energy of molecules, causing more frequent and energetic collisions, which speeds up the reaction.

15. Write the structural formula of methyl alcohol and mention its one use.

Structural formula: CH₃OH

Use: It is used as an industrial solvent and fuel additive.

16. Write any two differences between soap and detergent.

Soap	Detergent
Made from natural oils or fats	Made from synthetic chemicals
Works best in soft water	Works in both hard and soft water

Long answer type questions: [Group-D] [7X4=28]

17. Write any two positive and negative impacts of digital technology in human life.

Positive Impacts of digital technology in human life are:

The internet provides vast knowledge through search engines, online courses, and e-books.
Social media and instant messaging allow people to stay connected globally.

Negative Impacts of digital technology in human life are:

Digital technology has increased hacking, online fraud, and social media abuse.
Excessive screen time leads to eye strain, poor posture, and mental health issues.

18. What do you mean by endangered animals? Mention the cause of declining their number. Enlist the ways to protect them from being extinct.

The causes of declining the numbers of endangered animals are listed below:

Endangered animals are species that are at risk of extinction due to a rapid decline in their population.

a) Habitat destruction due to deforestation and urbanization.

b) Poaching and illegal wildlife trade.

c) Climate change affecting their natural habitat.

d) Pollution leading to water and air contamination.

The Ways to protect them from being extinct are listed below:

Establishing wildlife reserves and national parks.
Implementing strict anti-poaching laws.
Promoting conservation programs and awareness campaigns.
Reducing pollution and habitat destruction.

19. Draw the internal structure of the human heart and label its major parts.

20. Calculate how much heat is needed to raise the temperature of 500g of water from 50°C to 80°C.

Given:

Mass of water (m) = 500 g = 0.5 kg

Specific heat capacity of water (s) = 4200 J/kg°C

Initial temperature (T₁) = 50°C

Final temperature (T₂) = 80°C

Heat (Q) = ?

We know that;

21. If a student on the last bench of the class cannot read the letters written on the whiteboard clearly.

(a) Draw a diagram to show the defect of his eye.

(b) What is the cause of the defect?
Myopia (Short-sightedness) occurs due to:

Elongation of the eyeball, causing light rays to focus in front of the retina.
Increased curvature of the lens, making it too strong to focus correctly.

(c) Which lens is used to correct this defect? Why?
Concave lens is used because it diverges the incoming light rays, allowing the image to be focused on the retina.

22. Answer the following questions based on the electronic configurations of A and B.

Given:

A = 1s², 2s², 2p⁶, 3s², 3p⁶, 4s¹
B = 1s², 2s², 2p⁵

(i) In which group do elements A and B belong?
A belongs to Group 1 (Alkali metals) → Because it has one electron in the outermost shell.
B belongs to Group 17 (Halogens) → Because it has seven valence electrons.

(ii) Write the molecular formula of the compound formed by the combination of A and B.

The molecular formula of the compound formed by the combination of A and B is AB (NaCl)
A donates 1 electron, and B accepts 1 electron → The formula is AB (e.g., NaCl if A is sodium and B is chlorine).

(iii) Why is element B placed in the P-block of the periodic table?
Because its last electron enters the p-orbital (2p⁵).

23. Draw a well-labeled diagram of the laboratory preparation of ammonia gas and write the method to test this gas in a gas jar.

Test for Ammonia Gas:

Ammonia turns red litmus paper blue because it is basic in nature.
Ammonia produces dense white fumes when exposed to hydrogen chloride (HCl) gas.

SEE, PABSON, NPABSON Questions and Answer: Science