RBSE 10th Science Model Paper Set 7 with Answers in English

Students must start practicing the questions from RBSE 10th Science Model Papers Set 7 with Answers in English Medium provided here.

RBSE Class 10 Science Model Paper Set 7 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 which of the following groups of organisms, food materials are broken
down outside the body and then absorbed ? [1]
(a) Mushroom, Green plants, Amoeba
(b) Yeast, Mushroom, Bread mould
(c) Paramecium, Amoeba, Cuscuta
(d) Cuscuta, Lice, Tapeworm
Answer:
(b) Yeast, Mushroom, Bread mould

(ii) The site of photosynthesis in the cells of a leaf is ………………. .[1]
(a) chloroplast
(b) mitochondria
(c) cytoplasm
(d) protoplasm
Answer:
(a) chloroplast

(iii) Movement of sunflower in accordance with the path of sun is due to : [1]
(a) chemotropism
(b) geotropism
(c) phototropism
(d) hydrotropism
Answer:
(c) phototropism

(iv) Which gland secretes the growth hormone? [1]
(a) Pituitary gland
(b) Thyroid
(c) Hypothalamus
(d) Adrenal
Answer:
(a) Pituitary gland

(v) A fuse wire repeatedly gets burnt when used with a good heater. It is advised to use a fuse wire of: [1]
(a) more length
(b) less radius
(c) less length
(d) more radius
Answer:
(d) more radius

(vi) Coulomb is the SI unit of:
(a) charge
(b) current
(c) potential difference
(d) resistance
Answer:
(a) charge

(vii) The diagrams showing the correct path of the ray after passing through the convex lens: [1]

(a) II and III only
(b) I and II only
(c) I, II and III
(d) I, II and IV
Answer:
(c) I, II and III

(viii) Which of the following statements is true ? [1]
(a) A convex lens has 4 dioptre power having a focal length 0.25 m
(b) A ‘convex lens has -4 dioptre power having a focal length of 0.25 m
(c) A concave lens has 4 dioptre power having a focal length 0.25 cm.
(d) A concave lens has -4 dioptre power having a focal length 0.25 m.
Answer:
(a) A convex lens has 4 dioptre power having a focal length 0.25 m

(ix) The magnetic field inside a solenoid is: [1]
(a) non-uniform
(b) circular
(c) uniform
(d) none of these
Answer:
(c) uniform

(x) Which one of the following processes involves a chemical reaction ? [1]
(a) storing of oxygen gas under pressure in a gas cylinder
(b) liquification of air
(c) keeping petrol in a chinadish in open
(d) heating copper wire in presence of air at high temperature
Answer:
(d) heating copper wire in presence of air at high temperature

(xi) Acid present in apple is: [1]
(a) oxaclic acid
(b) mallic acid
(c) acetic acid
(d) formic acid
Answer:
(b) mallic acid

(xii) Which of the following are not ionic compounds ? [1]
(i) KCl
(ii) HCl
(iii) CCl₄
(d) NaCl
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iii)
Answer:
(b) (ii) and (iii)

2. Fill in the blanks:

(i) Largest part of the brain is …………………….. . [1]
Answer:
Cerebrum

(ii) Plants also show movement by ………………………… their roots and shoots bigger. [1]
Answer:
growing

(iii) Amrita Devi Bishnoi sacrificed her life for protpqtiep of ……………………. trees in Khejarli village. [1]
Answer:
Khejari

(iv) ……………………….. means growing single plant species in a forest. [1]
Answer:
Monoculture

(v) In spherical mirrors radius of curvature is ………………………. of the focal length [1]
Answer:
double

(vi) The current through a resistor is ……………………… proportional to its resistance. [1]
Answer:
inversely

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

(i) Which enzyme present in saliva breaks down starch ? [1]
Answer:
Salivary amylase (Ptyalin)

(ii) What are unicellular plants which float on the surface of water passively in a water body, called? [1]
Answer:
Phytoplanktons

(iii) Given an example of mixed gland. [1]
Answer:
Pancreas

(iv) What is growing of single forest trees, like pine, eucalyptus etc in a forest called? [1]
Answer:
Monoculture

(v) Why fossil fuels should be used judiciously ? [1]
Answer:
It is because these resources are limited, non renewable and polluting,

(vi) Convert 1 kwh into Joule. [1]
Answer:
1 kwh = 1000 × 3600 = 3.6 × 10⁶ Joule

(vii) Name the material which is generally used to make fuse wires. [1]
Answer:
Alloys of lead and tin or copper wire

(viii) What is the basic cause of induced emf ? [1]
Answer:
The basic cause of induced emf is the change of magnetic field in the circuit

(ix) Name the acid present in vinegar. [1]
Answer:
Acetic acid

(x) If the pH increases from 7 to 14, what does it show in terms of OH- ion concentration ? [1]
Answer:
OH^– concentration increases in the solution

(xi) Name one oxide which reacts with water to give an acid. [1]
Answer:
SO₂

(xii) Give the common method to get relief from the discomfort caused by ant sting. [1]
Answer:
To get relief one should apply any available basic salt eg, baking soda (NaHCCO₃) on it.

Part – B

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

Question 4.
Where do plants get each of the raw materials required for photosynthesis ? [2]
Answer:
The raw materials required by green plants for photosynthesis are carbon dioxide and water. The plants get Carbon dioxide from the atmosphere and water from the soil (aquatic plants get carbon dioxide dissolved in water).

Question 5.
Where are the genes located ? What is the chemical nature of genes ? [2]
Answer:
Genes are segments of the DNA, which is wound compactly into chromosomes. A gene is composed of a specific sequence of nucleotides. A nucleotide is made up of a nitrogenous base, a sugar molecule and a phosphate group.

Question 6.
How do embryological studies provide evidence for evolution? [2]
Answer:
The embryology of different vertebrates provide very strong evidence favoring organic evolution. The early embryos of different vertebrates show striking similarities. This indicates common origin and ancestry of different vertebrates. Thus, embryological studies provide direct evidence for evolution.

Question 7.
Why is excessive use of CFCs a cause of concern? [2]
Answer:
The use of the chemicals such as CFCs damages the ozone
layer and leads to its depletion. At the higher levels of the atmosphere, ozone performs an essential function, it shields the surfac of the earth from ultraviolet (UV) radiation from the sun. This radiation is highly damaging to organisms, since it is known to cause skin cancer in human beings.

Question 8.
List four properties of the image formed by a convex mirror. [2]
Answer:

• It is always formed behind the mirror, between the pole and its focus.
• It is always virtual and erect.
• Its size is always smaller than the object.
• Magnification is always positive.

Question 9.
Nichrome wire is used for making the heating elements of electrical appliances like iron, geyser etc. Give reasons. [2]
Answer:
Nichrome wire is used for making the heating elements of electrical appliances like iron, geyser etc, because:

• Nichrome has a very high resistance due to which it produces a lot of heat on passing current.
• It does not undergo oxidation easily even at high temperature due to which it can be kept red hot.

Question 10.
Two coils of resistance R₁ = 3Ω and R₂ = 9Ω are connected in series across a battery of potential difference 14 V. Find the electrical energy consumed in 1 minute in each resistance. [2]
Answer:
Given, R₁ = 3Ω, R₂ = 9Ω
R₃ = R₁ + R₂
= 9 + 3 = 12 Ω
Now I = \(\frac{V}{R_{3}}=\frac{14}{12}\)
= 1.167 Amp
Electric energy consumed in R₁
H₁ = I²R₁t
= (1.167)² × 3 × 60
H₁ = 245.14 J
Electric energy consumed in R₂
H₂ = I₂R₂t
= (1.167)² × 9 × 60
H₂ = 735.42 J

Question 11.
What is Maxwells corkscrew rule ? For what purpose is it used ? [2]
Answer:
According to Maxwell’s corkscrew rule : Imagine driving a corkscrew in the direction of current, then the direction in which we turn its handle is the direction of magnetic field.
This rule is used to determine the direction of magnetic field around a straight current carrying conductor.

Question 12.
How can nitrogen stop food items containing high fat and oil from turning rancid ? [2]
Answer:
Some high fat containing foods; such as potato chips are sealed in packets that are filled with nitrogen which is an unreactive gas. Nitrogen displaces oxygen gas in the packet and prevents the deterioration of fats in fatty foods because of oxidation process, which is the main cause of rancidity.

Question 13.
What does one mean by exothermic and endothermic reactions ? Give examples. [2]
Answer:
Exothermic reactions:
Reactions in which energy is evolved and rise in temperature takes place are called exothermic reactions.
Example : CaO + 2H₂O → Ca(OH)₂ + H₂ + Heat

Endothermic reaction: Reactions in which energy is absorbed are known as endothermic reactions.
Example: CaCO₃(s) + heat → CaO (s) + CO₂(g)

Question 14.
Differentiate between Roasting and calcination. [2]
Answer:

Roasting	Calcination
1. Heating in the presence of air.	Heating in the absence of air.
2. Sulphide ores are roasted.	Carbonate ores are calcined.
3. Sulphur dioxide is released 2ZnS + 3O2 → 2ZnO + 2SO2(g) 2PbS + 302 → 2PbO + + 2SO2(g)	Carbon dioxide is released.
4. Not used for dehydrating an ore.	Can be used to drive out’moisture from an ore.

Question 15.
Mention with reason the colour changes observed when:
(i) Silver chloride is exposed to sunlight.
(ii) Copper powder is strongly heated in the presence of oxygen. [2]
Answer:
(i) When silver chloride (white) is exposed to sunlight, it undergoes photochemical decomposition forming black metallic coloured silver and greenish yellow gas chlorine.
Thus, the change in colour is observed due to the oxidation of silver chloride in the presence of sunlight.

(ii) Heated copper metal reacts with oxygen to form the black copper oxide. Thus the change in colour is observed when copper powder is strongly heated.
2 Cu(s) + O₂(g) → 2 CuO(s)

Question 16.
During the reaction of some metals with dilute hydrochloric acid, the following observations were made by a student:
(a) Silver does not show any change.
(b) Some bubbles of a gas are seen when lead is reacted with the acid. [2]
Answer:
(a) Silver is covered with a thin layer of silver chloride, so it does not react with dilute hydrochloric acid.

(b) Bubbles of hydrogen gas are evolved when lead is reacted with the acid.
Pb + 2HC1 → PbCl + H₂

Part – C

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

Question 17.
When is blood clotting useful ? In a flow chart illustrate the four major events involved in blood clotting. [3]
OR
Given reasons for the following:
(i) Glottis is covered by epiglottis.
(ii) Lung alveoli are covered with blood capillaries.
(iii) The wall of trachea is supported by cartilage rings. [3]
Answer:
Usefulness of blood clotting.
(i) Plugging the place of injury.
(ii) Stoppage of blood flow from the region of injured blood vessel.

Question 18.
(a) What is variation? How is variation created in a population? How does the creation of variation in a species promote survival ?
(b) Explain how offspring and parents of organisms reproducing sexually have the same number of chromosomes ? [3]
OR
What is the law of dominance of traits ? Explain with an example. [3]
Answer:
(a) The difference in the characters among individuals of a species is called variation. ‘ A basic event in reproduction is the creation of a DNA copy. Cells use chemical reactions to build copies of their DNA. The DNA in the cell nucleus is the information source for making proteins. If the information is changed, different proteins will be made. Different proteins will eventually lead to altered body designs. This causes variations among the population.

The great advantage of variation to a species is that it increases the chances of its survival in a changing environment. For example, the accumulation of heat resistant variation in some ‘ bacteria will ensure its survival even when the temperature in its environment rises too much due to heat wave. On the other hand, the bacteria which did not have variation to withstand heat, would not survive.

(b) In sexual reproduction, organisms produce gametes through a special type of division, meiosis : reductional division, in which the original number of chromosomes becomes half. These two gametes then combine to form the zygote and original number of chromosomes is restored as in the case of human beings.

Question 19.
A coil of copper wire is connected to a galvanomerter. What would happen if a bar magnet is:
(i) pushed into the coil with its north pole entering first ?
(ii) pulled out of the bar magnet ?
(iii) held stationary inside the coil? [3]
OR
Draw a labelled diagram to explain the principle underlying the working of an electric generator. [3]
Answer:
(i) A deflection is observed in the galvanometer due to the induced current because of the changing magnetic flux (increasing) through the turns of the coil connected to the galvanometer,

(ii) A deflection is again observed in the glvanometer, as when it is pulled out, the flux linked with the coil due to the bar magnet decreases. Hence a current flows in the coil to reduce the change in flux. The deflection can be observed in the opposite direction as compared with the previous case.

(iii) No deflection is observed in the galvanometer. The flux linked with the coil due to the magnetic field is at a constant. Hence, no current is induced due to the bar magnet.

Question 20.
(i) What is the observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube ?
(ii) What type of reaction in this ?
(iii) Write a balanced chemical equation to represent the above reaction. [3]
OR
State the kind of chemical reactions in the following examples :
(i) Digestion of food in stomach
(ii) Combustion of coal in air
(iii) Heating of limestone [3]
Answer:
(i) A yellow precipitate of lead iodide is produced along with potassium nitrate solution.
(ii) Double displacement reaction.

Part – D

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

Question 21.
(a) Why is there a difference in the rate of breathing between aquatic organisms and terrestrial organisms ? Explain. [4]
(b) Draw a diagram of human respiratory system and label – pharynx, trachea, lungs, diaphragm and alveolar sac on it.
OR
(a) Name the organs that form the excretory system in human beings.
(b) Describe in brief how urine is produced in human body. [4]
Answer:
(a) There is a difference in the rate of breathing between the aquatic organisms and terrestrial organisms because the amount of dissolved oxygen in the water is much less than the amount on land so they have to breathe more in order to get more oxygen. The breathing rate of aquatic animals is faster than that of terrestrial animals because the amount of oxygen available in dissolved form is extremely low in concentration as compared to oxygen available in the air and the aquatic animals acquire oxygen that is dissolved in water. Oxygen is the necessary element for the survival of all organisms-on earth except anaerobes.

Question 22.
Draw the ray diagram in each case to show the position and nature of the image formed when the object is placed :
(i) at the centre of curvature of a concave mirror. [4]
(ii) between the pole P and focus F of a concave mirror.
(iii) in front of a convex mirror.
(iv) at 2F of a convex lens. [4]
OR
(a) With the help of a ray diagram explain why a concave lens diverges the
rays of a parallel beam of light.
(b) A 2.0 m tall object is placed perpendicular to the principal axis of a concave lens of focal length 15 cm. At what distance from the lens, should the object be placed so that it forms an image 10 cm from the lens? [4]
Answer:

Nature of image : Real, inverted and same size image is formed at the centre of curvature.

Nature of image : Virtual, enlarged and erect image is formed behind the mirror.

Nature of image : Virtual, erect and diminished, image is formed behind the mirror.

Nature of image : Real, inverted and of same size, image is formed at 2F on the other side.

Question 23.
(a) Write the name given to bases that are highly soluble in water. Give an example.
(b) Why does bee sting cause pain and irritation ? Rubbing of baking soda on the sting area gives relief. How ?
(c) How is tooth decay related to pH ? How can it be prevented ? [4]
OR
(a) What is universal indicator ?
(b) Write the chemical equation involved in the preparation of sodium hydroxide. Name the process.
(c) A farmer treats the soil with quicklime or calcium carbonate. What is the
nature of soil ? [4]
Answer:
(a) Alkali eq. NaOH (Sodium hydroxide)
(b) It is due to formic acid. Sodium hydrogen carbonate (Baking Soda) neutralises formic acid giving relief.
(c) Lower the pH, more will be tooth decay. Acid reacts with Ca₃(PO₄)₂ and causes tooth decay.
It can be prevented by brushing teeth after every meal.