RBSE 10th Science Model Paper Set 8 with Answers in English

Students must start practicing the questions from RBSE 10th Science Model Papers Set 8 with Answers in English Medium provided here.

RBSE Class 10 Science Model Paper Set 8 with Answers in English

Time: 2:45 Hours
Maximum Marks: 80

General Instructions to the Examinees:

• Candidate must write first his/her roll no. on the question paper compulsorily.
• All the questions are compulsory.
• Write the answer to each question in the given answer book only.
• For questions having more than one part the answer to those parts are to be written together in continuity.

Part – A

1. Multiple Choice Questions:
Choose the correct alternative for the following questions and write them in the answer book.

(i) In amoeba food is digested in the : [1]
(a) food vacuole
(b) mitochondria
(c) pseudopodia
(d) chloroplast
Answer:
(a) food vacuole

(ii) Blood from superior vena cava flows into : [1]
(a) right atrium
(b) right ventricle
(c) left atrium
(d) left ventricle
Answer:
(a) right atrium

(iii) What is the role of schwann cells in neuron? [1]
(a) Thermal insulation of neural axons
(b) Limit the speed of action potential
(c) Enhance the speed of impulse
(d) All of these
Answer:
(b) Limit the speed of action potential

(iv) Which of the following endocrine glands is unpaired ? [1]
(a) Adrenal
(b) Pituitary
(c) Testes
(d) Ovary
Answer:
(b) Pituitary

(v) The instrument used for measuring electric current is : [1]
(a) ammeter
(b) galvanometer
(c) voltmeter
(d) potentiometer
Answer:
(a) ammeter

(vi) Resistivity of a metallic wire depends on : [1]
(a) Its Length
(b) Its shape
(c) Its thickness
(d) Nature of material
Answer:
(d) Nature of material

(vii) The radius of curvature of a mirror is 20 cm, its focal length is : [1]
(a) 20 cm
(b) 10 cm
(c) 40 cm
(d) 5 cm
Answer:
(b) 10 cm

(viii) Convex lens forms a real, point-sized image at focus, the object is placed: [1]
(a) at focus
(b) between F and 2F
(c) at infinity
(d) at, 2F
Answer:
(c) at infinity

(ix) What should be the core of an electromagnet? [1]
(a) Soft iron
(b) Hard iron
(c) Rusted iron
(d) none of above
Answer:
(a) Soft iron

(x) On immersing an iron nail in CUSO4 solution for few minutes, you will observe: [1]
(a) no reaction takes place
(b) the colour of solution fades away
(c) the surface of iron nails acquire a black coating
(d) the colour of solution changes to green
Answer:
(d) the colour of solution changes to green

(xi) The difference of molecules of water in gypsum and POP is : [1]
(a) \(\frac{5}{2}\)
(b) 2
(c) \(\frac{3}{2}\)
(d) \(\frac{1}{2}\)
Answer:
(c) \(\frac{3}{2}\)

(xii) The bronze medals are made up of: [1]
(a) Cu and Zn
(b) Zn and Ni
(c) Cu and Sn
(d) Cu, Zn, Tn
Answer:
(c) Cu and Sn

2. Fill in the blanks: 1 × 6 = 6

(i) …………………. is the main thinking part of the human brain : [1]
Answer:
Fore brain

(ii) Ptyalin acts on the starch of the food and converts it into sugar ……………………….. [1]
Answer:
Maltose

(iii) …………………… means, hug the tree movement. [1]
Answer:
Chipko Andolan

(iv) ……………………… is a deadly poisonous gas. [1]
Answer:
Carbon monoxide

(v) Concave mirror is also known as …………………….. mirror. [1]
Answer:
Convergent resistance

(vi) …………………… is the hinderance offered in the path of electric current in the conductor. [1]
Answer:
electrical resistance

3. Very Short Answer Type Questions (Answer the questions in one word or one line):

(i) Name the muscular tube that connects each kidney with the bladder? [1]
Answer:
Ureter

(ii) Which plant hormone is responsible for the wilting and falling of leaves ? [1]
Answer:
Abscisic acid

(iii) What are the various steps of a food chain called ? [1]
Answer:
Trophic levels

(iv) Which pollutant would affect the capacity of blood in human being to absorb oxygen ? [1]
Answer:
Carbon monoxide, co

(v) State one reason for the conservation of forest and wildlife. [1]
Answer:
The conservation of forest and wildlife is necessary to restore the ecological balance

(vi) What is the best conductor of electricity ? [1]
Answer:
Silver

(vii) What is electric motor ? [1]
Answer:
A device which is used to convert electrical energy into mechanical energy

(viii) Name some sources of direct current. [1]
Answer:
Cells, batteries and DC generator

(ix) Name the natural source of lactic acid [1]
Answer:
Sour milk (Curd)

(x) A student detected the pH of four unknown solutions A, B, C and D as follows 11, 5, 7 and 2. Predict the nature of the solutions. [1]
Answer:
A is strongly basic, B is acidic, C is neutral and D is strongly acidic

(xi) Why cake or bread swells on adding baking powder ? Write chemical equration. [1]
Answer:
It is due to carbon dioxide

(xii) Name a salt which does not contain water of crystallisation. [1]
Answer:
Baking soda

Part – B

Short Answer Type Questions – Write the answer of questions 4 to 16 (Word limit 50 words) .

Question 4.
What processes would ytra consider essential for maintaining life ? [2]
Answer:
For maintaining life there must be a continuous input of energy and material into the body of the organism. Similarly the waste products produced are to be removed continuously. A state of homeostasis is to be maintained. All this can be maintained by nutrition, respiration, transportation, excretion and irritability. Reproduction ensures continuity of life.

Question 5.
How do homologous organs provide evidence in support of evolution ? [2]
Answer:
The presence of homologous organs indicates that all vertebrates have a common ancestry. Similarly, all organs and systems of the vertebrates show fundamental similarities which point towards common ancestry.

Question 6.
How do we know how old fossils are ? [2]
Answer:
We can find the relative age of the fossil by the depth at which the fossil is found. The ones that are found near the surface are more recent than the fossils found in the deeper layer. The second way of dating fossils is detecting the ratios of different isotopes of the same element in the fossil material.

Question 7.
What is biological magnification ? Will the level of this magnification be different at different levels of the ecosystem ? [2]
Answer:
Progressive increase in the concentration of harmful non- biodegradable substances at successive trophic levels of a food chain is called biological magnification. Yes, the level gradually increases. It is lowest at producer level but highest in top consumers, like human.

Question 8.
State two positions in which a concave mirror produces a magnified image of a given object [2]
Answer:
Position 1 – Between its pole and focus
Position 2 – Between the focus and centre of curvature.

Question 9.
Why is an electric bulb filled with argon and nitrogen gas ? [2]
Answer:
An electric bulb is filled with argon and nitrogen gas because they do not react with the hot tungsten filament and hence, prolong the life of the filament of the electric bulb.

Question 10.
Three resistors of 10 fl, 15 Ω and 5 Ω are connected in parallel. Find their equivalent resistance. [2]
Answer:
R₁ = 10 Ω, R₂ = 15 Ω, R₃ = 5 Ω Equvalent resistance
\(\frac{1}{R_{P}}\) = \(\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}}\)
\(\frac{1}{R_{P}}\) = \(\frac{1}{10}+\frac{1}{15}+\frac{1}{5}\)
\(\frac{1}{R_{P}}\) = \(\frac{3+2+6}{30}\)
= \(\frac{11}{30}\)
R_P = \(\frac{30}{11}\) = 2.72 Ω

Question 11.
Compare the magnetic field produced by a solenoid with that of a bar magnet ? [2]
Answer:
A coil of many circular turns of wire wrapped in the shape of a cylinder, is called a solenoid. The magnetic field lines in a solenoid, through which current is passed is very similar to that of a bar magnet. One end of the coil acts like a magnetic north pole, while the other acts like a south pole. The magnetic field produced by a long solenoid has all the properties of the field produced by a bar magnet.

Question 12.
When an iron knife is dipped in a solution of copper sulphate, a reddish brown layer gets formed on the knife. Explain. [2]
Answer:
Iron is more reactive metal than copper and displaces it from its solution of copper sulphate. The reddish brown layer seen on the knife is the deposit of displaced copper that is formed.

Question 13.
What happens when silver chloride is exposed to sun light ? Write a chemical equation for this reaction. Give one use of such a reaction. [2]
Answer:
When Silver chloride is exposed to sunlight colour of Silver chloride changes. On decomposition Silver chloride, which is white in colour, changes to grey.

Silver chloride decomposes into silver and chlorine.
This reaction is used in black and white photography.

Question 14.
Define the following terms [2]
(i) Mineral,
(ii) Ore.
Answer:
(i) Mineral: Most of the elements occur in nature in combined state called minerals. The chemical composition of minerals is fixed.

(ii) Ore: Minerals from
which metals can be extracted conveniently and profitably, are known as ores.

Question 15.
Name two metals which will displace hydrogen from dilute acids, and two metals which will not. [2]
Answer:
Metals that are more reactive than hydrogen displace it from dilute acids.
For example: Sodium and potassium.
Metals that are less reactive than hydrogen do not displace it.
For example: Copper and silver.

Question 16.
Give reasons:
(a) Sodium, potassium and lithium are stored under oil.
(b) Carbonate and sulphide ores are usually converted into oxides during the process of extraction. [2]
Answer:
(a) Sodium, potassium, and lithium are very reactive metals and react very vigorously with air as well as water. Therefore, they are kept immersed in kerosene oil in order to prevent their contact with air and moisture.

(b) Carbonate and sulphide ores are usually converted into oxides during the process of extraction because metals can be easily extracted from their oxides rather than from their carbonates and sulphides.

Part-C

Long Answer Type Questions – Write the answer of questions 17 to 20 (Word limit 100 words)

Question 17.
Draw a diagram of human alimentary canal and label – gall bladder, pancreas, liver and small intestine.
Give two reasons to explain why absolution of digested food occurs mainly in the small intestine? [3]
OR
What are stomata ? What governs the opening and closing of stomata. ? [3]
Answer:
(a) Human alimentary canal diagram:

(b) The small intestine is the most important part of the digestive system. Maximum absorption occurs in the small intestine because of the following reasons:
(i) Digestion is completed in the small intestine because the inner lining of the small intestine is provided with villi which increase the surface area for absorption of digested food.
(ii) Wall of the intestine is richly supplied with blood vessels which assimilate the absorbed food to the other parts of the body.

Question 18.
State one main difference between A.C and D.C. Why A.C is preferred over D.C. for long range transmission of electric power ? Name one source each of D.C. and A.C. [3]
OR
Explain why there are two separate circuits one for high power rating appliances and other for low power rater appliances. [3]
Answer:
Difference between A.C. and D.C. : The alternating current (A.C.) reverses its direction periodically whereas the direct current (D.C.) always flows in one direction.
A.C. is preferred over D.C. because it can be transmitted over long distances without much loss of energy.
D.C. source : Battery, D.C. generator
A.C. source : A.C generator

Question 19.
What is the law of dominance of traits ? Explain with an example. [3]
OR
Women are often blamed in our society for giving birth to girl child. What do you think ? How is sex in human determined ? [3]
Answer:
(a) According to this law, the characteristics (or traits) of an organism are determined by internal ‘factors’ which occur in pairs. Only one of a pair of such factors can be presented in a single gamete. This law explains expression of only one of the parental character in Fi generation and expression of both in F generation.
Example:
(i) Mendel first crossed purebred tall pea plants with purebred dwarf pea plants and found that only tall pea plants, were produced in the first generation or Fi generation. No dwarf pea plants were obtained in the first generation of progeny. From this Mendel concluded that the Fi generation showed the traits of only one of the parent plants: tallness being the dominant trait. The trait of other parent plant, dwarfness, being recessive did not show up in the progeny of first generation.

(ii) In the F₂ generation, both the tall and dwarf traits are present in the ratio of 3 : 1. This showed that the traits for tallness and dwarfness are present in the Fi generation. Dwarfness being the recessive trait does not express itself in the presence of tallness, the dominant trait.

Question 20.
Select:
(i) combination reaction,
(ii) decomposition reaction displacement reaction from the following chemical equations: [3]
(i) ZnC0₃(s) → ZnO(s) + C0₂(g)
(ii) Pb(s) + CuCl₂(aq) → PbCl₂(aqr) + Cu(s)
(iii) NaBr(aq) + AgNO₃(ag) → AgBr(s) + NaN0₃(aq)
(iv) H₂(g) + Cl₂(g) → 2HCl(g)
OR
Explain the following terms with one example each : [3]
(a) Corrosion
(b) Rancidity.
Answer:
(i) Decomposition reaction
(ii) Displacement reaction
(iii) Double displacement reaction
(iv) Combination reaction

Part – D

Essay Type Questions – Write the answers of question 21 to 23 (Word limit 250 words)

Question 21.
(i) How are water and minerals transported in plants. ?
(ii) How is food transported in plants ? [4]
OR
State the role played by the following in the process of digestion :
(i) Enzyme trypsin
(ii) Enzyme lipase
(b) List two functions of finger-like projections present in the small intestine. [4]
Answer:
Horizontal transportation, i.e.
from root hair to xylem takes place by simple diffusion arid osmosis from cell to cell. Upward or vertical transportation of water and dissolved minerals takes place through xylem. The xylem vessels form a continuous tube like structure from roots to the top of the plant.

Water taken to the leaves by the xylem is constantly evaporated from the leaf surface through stomata. As water forms a continuous column from root to the leaves, the loss of water from leaves creates a negative pressure or suction at the leaves. At the soil level the pressure remains constant. Due to this pressure difference water and dissolved minerals flow in upward direction. Therefore, water moves up in plants due to transpiration pull. Some properties of water and chemical nature of xylem also helps in this conduction of water.

The food prepared in photosynthesis is transported in the form of sucrose sugar through phloem to all parts of the plant. This transport is called translocation, and it requires energy in the form of ATP. The mechanism of transportation of food is as follows:
The food prepared in the mesophyll cells of leaf is loaded actively into sieve tube in the form of sucrose. Energy in the form of ATP is required for this active loading. Once the sugar enters the mesophyll cell the osmotic pressure of these cells increases. Therefore, water also flows into them by osmosis. The mixture of sugar and water increases the pressure in the sieve tubes. This solution is transported to areas which have less pressure (Sink). The movement of food in phloem may be in downward or upward direction. It depends – on the requirement of the plant. Uploading of this sugar into tissues also needs energy.

Question 22.
(a) If the image formed by a lens is dimimished in size and erect, for all positions of the object, what type of lens is it ?
(b) Name the point on the lens through which a ray of light passes undeviated.
(c) An object is placed perpendicular to the principle axis of a convex lens of
focal langth 20 cm. The distance of object from the lens is 30 cm. Find (i) the position (ii) the magnification. [4]
OR
(a) What is meahf by power of lens?
(b) State and defmi the S.I unit of power of a lens. :
(c) A convex leits’bf focal length 25 cm and a Concave lens of focal length 10 cm. are platcted’ih close contact with each other. Calculate the lens power of this combination. [4]
Answer:
(a) Concave lens
(b) Optical centre
(c) Here, u = – 30 cm, f = 30 cm
(i) Using 7 = \(\frac{1}{f}\) = \(\frac{1}{v}-\frac{1}{u}\) , we get
= \(\frac{1}{v}\) = \(\frac{1}{f}+\frac{1}{v}\)
= \(\frac{1}{20}+\frac{1}{-30}\)
= \(\frac{3-2}{60}\)
υ = 60 cm
Image is formed at a distance of 60 cm from the lens on its right side

(ii) m = \(\frac{v}{u}\) = \(\frac{60}{-30}\) = -2

Question 23.
(a) Crystals of a substance changed their colour on heating in a closed test . tube but regained it after sometime when they were allowed to cool down. Name the substance and write its formula and explain the phenomenon involved.
(b) Name the compound whose one formula unit is associated with 10 water molecules. How is it prepared ? Give equations of related reactions. [4]
OR
What are strong and weak acids ? In the following list of acids, separate strong acids from weak acids.
Hydro chloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid. [4]
Answer:
(a) CuSO₄ . 5H₂O is a blue crystalline solid. It becomes dirty white on heating due to loss of water molecules and it becomes amorphous.

It regains its colour by absorbing water from atmosphere and . becomes blue in colour
CuSO₄ + 5H₂O → CUSO₄.5H₂O
Blue

(b) Na₂ C0₃.10H₂O. It is called sodium carbonate decahydrate or washing soda It is prepared by passing CO₂ gas through saturated solution of ammonical brine.
NH₃ + H₂O + CO₂ + NaCl → NaHCO₃ + NH₄Cl