SEE (Secondary Examination Board)

Subject: Science & Technology

Model Set 1 Solution

RE-1041

1.     Write the correct alternative of the following questions in the answer sheet.

a)     Which is the smallest unit of computer memory?

Bit

b)    Why is pines kept in sub-division gymnosperm.

It has naked seeds.

c)     Which of the following groups of organisms are closely related on the basis of evolution?

Platyhelminthes, Nemathelminths, Annelida

d)    What is the main cause of increasing the level of ocean?

Increase in the temperature of the earth.

e)    Calculate the mass that a person can lift on moon if he can lift a mass of 50kg on the earth. The value of g on the surface of the Earth is 9.8m/s² and that of moon is 6 times less.

Given,

Here on the earth,

Mass of the body on the earth (m_e) = 50kg

Acceleration due to gravity on the earth(g_e)=9.8m/s²

Weight(W) = ?

We have,

W=m_e x g_e

Or, W = 50 x 9.8 = 490N

The person can lift 490N on the earth. As the person has capacity of lifting 490N.

On the moon, we have

Weight(W)=490N

Acceleration due to gravity on the moon(g_m)=1.633m/s²

Mass that can be lifted on the moon(m_m)=?

We have,

W=m_m x g_m

Or, 490 = m_m x 1.633

Or, m_m = 490/1.633 = 300.061kg

f)      If large piston A and small piston B of a hydraulic lift have their cross-sectional are, pressure and force/weight are A₁and A₂, P₁ and P₂ and F₁ and F₂ respectively, then which of the following relation would be correct according to Pascal’s law? 

F₁ > F₂

g)     Identify   the   characteristics   of   the image of the object XY kept in front of the lens as shown in the given figure.

Real, inverted and magnified.

h)    Which of the following is proved by Hubble's law?

Universe is expanding.

i)      Which one is a double displacement reaction from the following?

XY + AB  à   XB + AY

j)      A statement and two arguments are given below.

Detergent is called a soap less soap.

Argument-1: It  has  cleaning  properties  like  soap  but  its  chemical nature is different.

Argument-2: It does not give lather with hard water as soap.

Statement  and  argument  1  is  correct  but  argument  2  is incorrect.

(Group ‘B’)

2.     Write very short answer of the following questions:            9x1=9

a)     Write an advantage of independent variable.

It can explain outputs and predict the values of dependent variables.

b)    What is upthrust?

When a body is totally or partially immersed inside the liquid, it experiences an upward force given by the liquid, which is called as upthrust.

c)     Write down one utility of optical fiber.

Optical fiber can be used to transmit images, telephone calls, video signals and computer data.

d)    In summer season, the cemented roads are seemed to be filled with water but they are not actually. Which phenomenon of light is behind this?

This phenomenon is called as mirage.

e)    What happens when carbon dioxide gas is passed through lime water for short time?

When carbon dioxide gas is passed through lime water for short time, the solution turns milky due to the formation of insoluble calcium carbonate.

Ca(OH)₂ + CO₂ à CaCO₃ + H₂O

f)      What is meant by redshift?

Redshift is the displacement of the spectrum of an astronomical object towards longer(red) wavelengths.

g)     Write the name of main ore of silver.

Argentite (Ag₂S) is the main source of silver.

h)    Why are group VII elements of periodic table called halogens?

Group VIIA elements are called as halogens because they form salt with group IA or IIA elements.

i)      Write the structural formula of glycol.

(Group ‘C’)                        14x2=28

Write short answer questions.

3.     Use fundamental units to show that equation P = IV is homogeneous, where I is electric current, V is voltage and P is power.

4.     Write any two characteristics of plant kingdom.

Any two characters of plant kingdom are:

a)     They store food in the form of starch.

b)    They are multicellular eukaryotes.

5.     Write any two roles of honey bee on ecosystem.

 Any two roles of honey bee on ecosystem are:

a)     They pollinate the plants.

b)    They increase the yields and give rise to lucrative honey industry.

6.     Mitosis cell division is called equational division. Why?

Mitosis cell division is called as equational cell division because the number of chromosomes in mother cell is equal to the number of chromosomes in daughter cells.

7.     India has donated Murrah Buffalo to Nepal. Mention any two benefits gained by farmers on breeding buffalo with Murrah buffalo instead of local species of buffaloes.

Two benefits gained by farmers on breeding buffalo with Murrah buffalo instead of local species of buffaloes:

a)     It is known for higher yielding of milk.

b)    It has high heat resistive power.

8.     Write any two differences between hemophilia and leukemia.\

9.      Number of red panda is decreasing in Nepal. What measures can be done to protect the Panda? Write any two measures.

Any two measures to protect the panda are as follow:

a)     Illegal poaching should be stopped.

b)    We should protect their habitat.

10.  Write any two factors on which gravity on the surface of a heavenly body depends.

Any two factors on which gravity on the surface of a heavenly body depends are:

·       Distance between their centres.

·       Product of the masses of bodies.

11.   Prove that if the earth attracts two bodies placed at the same distance from the centre of the earth with the same force, then their masses are equal.

12.  Lamp is lit in the running bicycle by the help of a dynamo but it goes off when bicycle is stopped. Give reason.

When the bicycle is running, due to change in magnetic flux inside the dynamo, current is induced and hence the lamp is lit. But, when the bicycle stops, the magnetic flux does not change and current is not generated, so, the lamp goes off.

13. 
In domestic house hold wiring voltage of 220V is supplied. A battery of mobile works with 3.7 V. Draw net diagram of transformer used in mobile charger.

14.  Write a balanced chemical equation between the reactions of a metal of group IIA with a non-metal of group VIIA.

Mg + Cl₂      à     MgCl₂

15.  Write the name of members of alkyne which contains an equal number of hydrogen and carbon. Write one uses of it.

The name of the members of alkyne which contains an equal number of hydrogen and carbon is acetylene (ethyne). Its one use is, it is used to manufacture acetic acid.

16) "It is dangerous to use chemical pesticides for human health. Justify this statement by using your two arguments.

It is dangerous to use chemical pesticides for human health because of following reasons.

a)     It is a poison for human health.

b)    It causes skin or eye irritation.

(Group ‘D’)                              7x4=28

17) Write any two positive and negative impacts of digital technology in our daily life.

Any two positive impacts of digital technology are:

a)     It connects people globally.

b)    It enhances communication.

Any two negative impacts of digital technology are:

a)     It may create digital addiction. 

b)    It may create cyber crimes.

18) Study the figure and answer the following questions.

a.   What   is   the   special property     of     water shown   in   the   figure called?

This is called as anomalous expansion of water.

b.   Write the change that takes place in volume of water on heating from 0⁰C to 10⁰C.

The volume of water decreases from 0⁰C to 4⁰C and from 4⁰C to 10⁰C the volume of water increases.

c.   Write one use of this special property of water.

In the cold places aquatic organisms can survive even if the surface of water is frozen.

19)  A) What is an artery? Name the largest artery of   human body.

      Artery is the blood vessel that carry blood away from the heart. The largest artery of human body is aorta.

B) Write two causes of high blood pressure.

Any two causes of high blood pressure are:

a)     Smoking cigarettes and use of tobacco.

b)    Excessive drinking of alcohol.  

20) In the figure, A, B and C are three metal objects of equal mass and volume. They are heated to the same temperature and then placed in a vessel containing solid wax. The specific heat capacity of A, B and C are 380J/kg⁰C, 470 J/ kg⁰C and 910J/ kg⁰C respectively. Based on this information, answer the following questions.

a)     Which metal has the highest amount of heat energy?

Given,

Mass = m, heat energy = Q , specific heat capacity =s, difference in temperature = dt

We have

Q = msdt

M and dt are constants. Removing the constants

Q α s

Heat energy is directly proportional to specific heat capacity.

Hence, C has highest amount of heat energy.

b)    Which metal goes the deepest into the wax vessel?

Given,

Mass = m, heat energy = Q , specific heat capacity =s, difference in temperature = dt

We have

Q = msdt

M and dt are constants. Removing the constants

Q α s

Heat energy is directly proportional to specific heat capacity.

Hence, C has highest amount of heat energy. So, it will melt the wax more.

c)     Which metal cools down the fastest?

Given,

Mass = m, heat energy = Q , specific heat capacity =s, difference in temperature = dt

We have

Q = msdt

M and dt are constants. Removing the constants

Q α s

Heat energy is directly proportional to specific heat capacity.

Hence, A will cool down faster.

d)    Which metal has the highest amount of heat lose?

Given,

Mass = m, heat energy = Q , specific heat capacity =s, difference in temperature = dt

We have

Q = msdt

M and dt are constants. Removing the constants

Q α s

Heat energy is directly proportional to specific heat capacity.

Hence, C has highest amount of heat energy. So, it will lose heat more.

21) Write two differences between concave and convex lens. The power of the lens used in the spectacles worn by a student is - 6D. Calculate the focal length of the lens. Also, mention the type of lens.

                        Given,

Power of lens (P) = -6D

Focal length (f) = ?

We have,,

Power of lens (P) = 1/f(in m)

            Or, -4D = 1/f(in m)

            Or, f =1/-4

            Or, f = -0.25 m .

The focal length of lens is -0.25m. It is a concave lens.

22) Study  the  electronic  configuration  of  two  elements  X  and  Y  and answer the given questions.

          a)     Which one is metal ?

X is a metal.

b)    Write period of the element Y.

Y is chlorine. Its atomic number is 17(2,8,7) . so, the period is 3.

c)     Write  balanced chemical equation of the  compound formed  by combination of X and Y.

Ca + Cl₂ à CaCl₂

23) Study   the   given   diagram   and answer the following questions.

a)     Which gas is being collected in gas Jar?

Ammonia gas (NH₃) is being collected in the gas jar.

b)    What are A & B in the figure?

A is CaO (Calcium Oxide). B is the mixture of ammonium chloride(NH₄Cl) and calcium hydroxide [Ca(OH)₂]

c)     What coloured litmus paper is used to identify such gas?

Red coloured litmus paper is used to identify such gas.