RBSE 10th Science Model Paper Set 4 with Answers in English

Students must start practicing the questions from RBSE 10th Science Model Papers Set 4 with Answers in English Medium provided here.

RBSE Class 10 Science Model Paper Set 4 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) Which is the correct sequence of parts in human alimentary canal ? [1]
(a) Mouth → Stomach → Small intestine → Large intestine
(b) Mouth → Oesophagus → Stomach → Large intestine → Small intestine
(c) Mouth → Stomach → Oesophagus → Small intestine → Large intestine
(d) Mouth → Oesophagus → Stomach → Small intestine → Large intestine.
Answer:
(d) Mouth → Oesophagus → Stomach → Small intestine → Large intestine.

(ii) If salivary amylase is lacking in the saliva, which of the following events in the mouth cavity will be affected ? [1]
(a) Proteins breaking down into amino acids
(b) Starch breaking down into sugar
(c) Fats breaking down into fatty acids and glycerol
(d) Absorption of vitamins
Answer:
(b) Starch breaking down into sugar

(iii) Electrical impulse travels in a neuron from: [1]
(a) Dendrite → axon → axonal end → cell body
(b) Cell body → dendrite → axon → axonal end
(c) Dendrite → cell body → axon → axonal end
(d) Axonal end → axon → cell body → dendrite
Answer:
(c) Dendrite → cell body → axon → axonal end

(iv) In a neuron, conversion of electrical signal into a chemical signal occurs at/in: [1]
(a) Cell body
(b) Axon end
(c) Dendrite end
(d)Axon
Answer:
(b) Axon end

(v) Which of the following lenses would you prefer to use while reading small
letters found in a dictionary ? [1]
(a) A convex lens of focal length 50 cm
(b) A concave lens of focal length 50 cm
(c) A convex lens of focal length 5 cm
(d) A concave lens of focal length 5 cm
Answer:
(c) A convex lens of focal length 5 cm

(vi) In torches, searchlights and headlights of vehicles the bulb is placed: [1]
(a) between the pole and the focus of the reflectors
(b) very near to the focus of the reflector
(c) between the focus and centre of curvature of the reflector
(d) at the centre of curvature of the reflector
Answer:
(b) very near to the focus of the reflector

(vii) An electric bulb is rated 220 V and 100 W. When it is.operated on 110 V, the power consumed will be: [1]
(a) 100 W
(b) 75 W
(c) 50 W
(d) 25 W
Answer:
(d) 25 W

(viii) Two resistors of resistance 2Ω and 4Ω when connected to a battery will have: [1]
(a) Same current flowing through them when connected in series
(b) Same current flowing though them when connected in parallel
(c) Same potential difference across them when connected in series
(d) Different potential difference across them when connected in parallel
Answer:
(a) Same current flowing through them when connected in series

(ix) Magnetic field inside a solenoid is: [1]
(a) directly proportional to its length
(b) directly proportinal to current
(c) inversely proportional to total number of turns
(d) inversely proportional to current
Answer:
(c) inversely proportional to total number of turns

(x) The following reaction is used for the preparation of oxygen gas in the laboratory: [1]

Which of the following statement (s) is are correct about the reaction ?
(a) It is a decomposition reaction and endothermic in nature
(b) It is a combination reaction
(c) It is a decomposition reaction and accompained by release of heat
(d) It is a photochemical decomposition reaction and exothermic in nature
Answer:
(a) It is a decomposition reaction and endothermic in nature

(xi) Baking soda is a mixture of: [1]
(a) Sodium carbonate and acetic acid
(b) Sodium carbonate and tartaric acid
(c) Sodium hydrogen carbonate and tartaric acid
(d) Sodium hydrogen carbonate and acetic acid
Answer:
(c) Sodium hydrogen carbonate and tartaric acid

(xii) Which of the following methods is suitable for preventing an iron frying pan from rusting ? [1]
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) All of the above
Answer:
(c) Applying a coating of zinc

2. Fill in the blanks:

(i) ………………….. hormone is responsible for the elongation of cells. [1]
Answer:
Auxins

(ii) The opening and closing of the pore is a function of the ………………….. . [1]
Answer:
Guard cells

(iii) ………………… gas is released by the burning of coal and petroleum which adds to global warming: [1]
Answer:
Carbon dioxide

(iv) The scientific method of growing of forest trees is called …………………… [1]
Answer:
Silviculture

(v) Colour is the function of frequency not the ………………….. of light. [1]
Answer:
Wavelength

(vi) The SI unit of resistivity is ……………………. [1]
Answer:
Ohm-meter

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

(i) What makes the inactive pepsin of gastric juice active ? [1]
Answer:
HCl (Hydrochloric acid)

(ii) What are directional growth movements called ? [1]
Answer:
Tropic movement

(iii) Name any two artificial ecosystems. [1]
Answer:
An aquarium, A park

(iv) What are the two broad categories of natural resources ? [1]
Answer:
Inexhaustible and exhaustible, renewable and non renewable

(v) What type of bacteria inhabiting intestine of human being pollute water ? [1]
Answer:
Escherichia coli

(vi) Name the device which is used to measure current in the circuit.
Answer:
Ammeter

(vii) Give the factors that affect strength of magnetic field at a point due to a straight conductor carrying current. [1]
Answer:
Magnitude of electric current, perpendicular distance between that point and conductor

(viii) Write the principle on which AC generator works.
Answer:
AC generator works on the principle of electromagnetic induction

(ix) Name two organic acids. [1]
Answer:
Citric acid, lactic acid

(x) What is common to all acids ? [1]
Answer:
Hydrogen

(xi) Name a base which is not an alkali. [1]
Answer:
Copper hydroxide, Cu(OH)₂

(xii) What happens when nitric acid is added to egg shell ? [1]
Answer:
Egg shells contain calcium carbonate. When nitric acid is added to it, carbon dioxide gas is evolved.

Part – B

Short Answer Type Questions – Write the answer of questions no. 4 to 16 (Word limit 50 words)

Question 4.
What is the advantage of having four-chambered heart ? [2]
Answer:
In four-chambered heart there is complete separation of oxygenated and deoxygenated blood, i.e. there is no mixing of blood. Therefore, the body parts receive oxygenated blood only loaded with oxygen. Animals having four-chambered heart are warm blooded and maintain high metabolic rate. This homeostasis can be maintained if the organs get rich oxygen supply. The four-chambered heart ensures complete separation of blood and good supply of oxygen, (as in birds and mammals).

Question 5.
Give an example of the characteristics being used to determine how close two species are in evolutionary terms. [2]
Answer:
To determine the closeness of species following characteristics may be used:

• Molecular phylogeny, fossil record etc.
• Classification of species is in fact a reflection of their evolutionary relationship.
  This classification is based on-cell design, unicellular/ multicellular; photosynthetic/ heterotrophic, skeleton inside the body/around the body etc.

Question 6.
What are fossils ? What do they tell us about the process of evolution ? [2]
Answer:
Remains or remnants of the organisms of the remote past are known as fossils. The fossils are important evidence of organic evolution. They help us to trace evolutionary history of a group of organisms. They also tell us about evolutionary relationship among organisms. They are rightly called written documents of evolution.

Question 7.
Differentiate between biodegradable and non-biodegradable substances. Give examples. [2]
Answer:
Biodegradable substances are degraded (decomposed) by decomposers, in nature, into simpler inorganic substances. They are of plant or animal origin.
For example-Vegetable waste, paper, cow dung etc. Non-biodegradable substances cannot be decomposed by microbes or other living organisms into simpler, harmless substances. Therefore, they keep on accumulating in the environment and create problem of waste disposal.
For example-Plastic, DDT etc.

Question 8.
Which factors determine the focal length of a lens ? [2]
Answer:
The focal length of a lens depends on :

• Radii of curvature of the surfaces of the lens.
• Nature of the material of the lens.
• Nature of medium in which lens is placed.

Question 9.
When a 12 V battery is connected across an unknown resistor, there is a current of 2*5 mA in the circuit, find the value of the resistor. [2]
Answer:
Given,V = 12 volt
I = 2.5 mA = 2.5 × 10³ A
R = \(\frac{\mathrm{V}}{\mathrm{I}}\) = \(\frac{12 \mathrm{~V}}{2.5 \times 10^{-3} \mathrm{~A}}\)
= 4800 Ω
= 4.8 kΩ

Question 10.
Define resistivity and write its SI unit. [2]
Answer:
Given,V = 12 volt
I = 2.5 mA = 2.5 × 10³ A
R = \(\frac{\mathrm{V}}{\mathrm{I}}\) = \(\frac{12 \mathrm{~V}}{2.5 \times 10^{-3} \mathrm{~A}}\)
= 4800 Ω
= 4.8 kΩ

Question 11.
What does the direction of thumb indicate in the right hand thumb rule ? In what way this rule is different from Fleming’s left hand rule ? [2]
Answer:
In right hand thumb rule, thumb indicates the direction of current in the straight current-carrying conductor. This rule is quite different from Fleming’s left hand rule in the way that Fleming’s left hand rule thumb gives the direction of force experienced by a current-carrying straight conductor placed in an external magnetic field.

Question 12.
What is an oxidising agent ? What happens when an oxidising agent is added to propanol ? Explain with the help of a chemical equation. [2]
Answer:
Oxidising agent is a substance which can give oxygen to other substance. When an oxidising agent is added to propanol it is oxidised to propanoic acid.

Question 13.
What is the difference between combination and decomposition reactions ? Write equations for these reactions. [2]
Answer:
In a combination reaction, two elements or compounds combine to form, a new compound, whereas in decomposition reactions, a compound decomposes to give two or more elements or compounds.

Thus, combination and decomposition reactions are opposite of each other : Combination reaction :
2Mg(s) + O₂(g) → 2MgO(s)
Decomposition reaction:
CaCO₃(s) → CaO(s) + CO₂(g).

Question 14.
What are amphoteric oxides ? Give two examples of amphoteric oxides ? [2]
Answer:
Those oxides that behave as both acidic and basic oxides are called amphoteric oxides.
For example: Aluminium oxide (Al₂O₃), Zinc oxide (ZnO).

Question 15.
(a) Write the electronic configuration of nitrogen and chlorine atoms.
(b) Show the formation of sodium chloride by the transfer of electrons between nitrogen and chlorine atoms. [2]
Answer:
(a) Nitrogen → Atomic number 7 (2, 5)
Chlorine → Atomic number 17 (2, 8, 7)

Question 16.
The following reaction takes place when aluminium powder is heated with MnO₂ :
3MnO₂ (s) + 4Al (s) → 3 Mn(l) + 2Al₂O₃ (l) + Heat
(a) Is aluminium getting reduced ?
(b) Is MnO₂ getting oxidised ? [2]
Answer:
(a) No, because oxygen is added to aluminium therefore, it is getting oxidised.
(b) No, since manganese has lost oxygen therefore it is getting reduced.

Part – C

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

Question 17.
Draw the structure of a Nephron. Explain how the structure of a nephron is very well suited to its function. [3]
OR
Draw a labelled diagram showing excretory system of human being. How is the amount of urine produced regulated ? [3]
Answer:

Structure of nephron is very well adapted to its function. The nephron is the functional unit of kidney and its function is production of urine by filtration of blood. This process has two main steps-Ultrafiltration and Reabsorption. The nephron has Bowman’s capsule for ultrafiltration. This capsule has a tuft of capillaries closely applied to its thin walls. The blood is filtered in it. Each nephron has a long tubular portion for the re¬absorption of excess water and useful substances like amino acids, glucose etc.

Question 18.
Draw a labelled circuit diagram of a simple electric motor and write its construction. [3]
OR
Draw a sketch for field lines around a bar magnet. How do you find field lines? [3]
Answer:

Construction
(i) Armature: The rotating part of the motor, including the electromagnets, is called the armature. Basically it consists of a large number of turns of insulated copper wire wounded over a soft iron core.

(ii) Field Magnet: Armature coil is placed between the North and South poles of two permanent magnets which produces a strong magnetic field.

(iii) Split ring or commutator: The wires from each of the three coils are attached to three metal plates called commutator at the end of armature. In the DC motor, the two halves of a metallic ring R₁ and R₂ are connected with the two ends of armature coil. They work as commutator. These rotate with the coil and reverse the direction of current flowing through the coil every time the coil just passes the vertical position during a revolution.

(iv) Carbon brushes: There are two flexible carbon brushes Bi and B2 which are so fixed that when the rotor spins, the three plates come into contact with the positive and negative brushes. Electric current flows through the brushes into the coils.

(v) Battery: It is connected across the brushes.

Question 19.
How do Mendel’s experiments show that traits are inherited independently ? [3]
OR
How is the equal genetic contribution of male and female parents ensured in the progeny? [3]
Answer:
To prove that traits are inherited independently we need to consider the inheritance of two traits simultaneously. This can be done by studying dihybrid cross. If we take the hybrid of a dihybrid cross as parent and selfed them then the different genes of both the traits inherit independent of each other. For example, a hybrid yellow and round parent would produce four type of gametes.

This cross shows that during gamete formation the gene of roundness can go with yellow colour or green colour. It does not remain stuck to yellow colour gene. Similarly, gene for wrinkledness can also go with green colour or yellow colour. It means they inherit independently and randomly fuse with other gametes. It gives a ratio of 9 : 3 : 3 : 1.

Question 20.
Give the characteristic tests for the following gases:
(a) CO₂
(b) SO₂
(c) O₂
OR
Write the balanced chemical equations for the following reactions : 3
(a) Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogen carbonate.
(b) Sodium hydrogen carbonate on reaction with hydrochloric acid gives sodium chloride, water and liberates carbon dioxide.
(c) Copper sulphate on treatment with potassium iodide precipitates cuprous iodide (CU2I2), liberates iodine gas and also forms potassium sulphate.
Answer:
The characteristic test:
(a) Carbon dioxide (CO₂) gas turns lime water milky when passed through it due to the formation of insoluble calcium carbonate.

(b) Sulphur dioxide (SO₂) gas when passed through acidic potassium permanganate solution (purple in colour) turns it colourless because SO₂ is a
strong reducing agent

or Sulphur dioxide gas when passed through acidic dichromate solution (orange in colour) turns it to green because sulphur dioxide is a strong reducing agent.

(c) The evolution of oxygen (O₂) gas during a reaction can be confirmed by bringing a burning candle near the mouth of the test tube containing the reaction mixture. The intensity of the flame increases because oxygen supports burning.

Part – D

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

Question 21.
(i) What are plant hormones ?
(ii) Write the causes of movement in plants. [4]
OR
(i) What is the need for a system of control and coordination in an organism?
(ii) How does chemical coordination occur in plants ? [4]
Answer:
(i) The chemical substances produced by plants to control and coordinate various events of their life cycle like germination of seeds, growth, development, flowering, fruiting and response to stimuli are called plant hormones. Examples are- auxins, gibberellins, cytokinins and abscisic acid etc.

(ii) As plants are rooted at a place, they do not show locomotion, i.e. they do not move from one place to the other. However, parts of the plant like roots, stem and leaves show some movement. It means, that there is some change in their position while still attached to the rooted plant. Plants show response to stimuli like water, light, gravity, seasonal variations, chemical, touch etc.

The causes of movement in plant may be:
(a) Growth : Some movments are essentially growth movements. They are caused due to unequal growth of the plant parts.
(b) Change in , Turgor Pressure : Some movements are caused by change in turgor pressure. Cells become turgid when they gain water and become flaccid when they loose water. This change causes movement in some plants.
(c) Plant Movements in Response to External Stimuli : Plant movements in response to external stimuli can be divided into two categories : tropic movements and nastic movements.

Question 22.
List the sign conventions for reflection of light by spherical mirrors. Draw a
diagram and apply these conventions in the determination of focal length of a spherical mirror which forms a three times magnified real image of object placed 16 cm in front of it. [4]
OR
State the law of refraction of light that defines the refractive index of a medium with respect to the other. Express it mathematically. The refractive indices of glass and water with respect to vaccum are 3/2 and 4/3 respectively. If the speed of light in glass is 2 × 10 m/s, find the speed of light in vaccum and water. [4]
Answer:
Sign conventions for reflection of light by spherical mirror are:

1. The object is always placed to the left of the mirror.
2. All the distances parallel to the principal axis are always measured from the pole of the spherical mirror.
3. All the distances’ measured along the direction of incident light (along + ve X-axis) are considered to be positive.
4. Those distances measured opposite to the direction of incident light (i.ealong – ve X-axis) are taken as negative.
5. The distances measured in upward direction, i.e. perpendicular to and above the principal axis (along + ve y-axis) are taken as positive.
6. The distances measured in the downward direction, (along – ve y axis), i.e. perpendicular to and below the principal axis are take as negative.

From the question
u = – 16 cm,
m = – 3 for real image
But m = \(\frac{-v}{u}\) = -3
υ = 3u = – 3(- 16)
= – 48 cm
Using mirror formula
\(\frac{1}{f}=\frac{1}{v}+\frac{1}{u}\)
We get \(\frac{1}{f}\) = \(\frac{1}{-48}+\frac{1}{-16}\)
= \(\frac{-1-3}{48}\)
= \(\frac{-4}{48}=\frac{-1}{12}\)
f = – 12 cm

Question 23.
Equal length of magnesium ribbon are taken in two test tubes ‘A’ and ‘B’. H₂O₄ is added to test tube ‘A’ and H₂CO₃ in the test tube ‘B’ in equal amounts:
(a) Identify the test tube showing vigorous reaction.
(b) Give reason to support your answer.
(c) Name the gas liberated in both the tubes. How will you prove its liberation?
(d) Write chemical equations for both reactions. [4]
OR
Describe an activity with diagram to illustrate that the reaction of metal carbonates and metal bicarbonates with acids produces carbon dioxide. Write the relevant equations of all the reactions that take place. [4]
Answer:
(a) A will show vigorous reaction.
(b) It is because H₂SO₄ is a strong acid.
(c) Hydrogen gas will be formed. Bring a burning splinter near the gas. It will burn with ‘por’ sound.
It shows gas liberated as hydrogen.
(d) Mg + H₂SO₄ → MgSO₄ + H₂↑
Mg + H₂CO₃ → MgCO₃ + H₂↑