RBSE 10th Science Model Paper Set 9 with Answers in English

Students must start practicing the questions from RBSE 10th Science Model Papers Set 9 with Answers in English Medium provided here.

RBSE Class 10 Science Model Paper Set 9 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) During respiration exchange of gases takes place in : [1]
(a) trachea and larynx
(b) alveoli of lungs
(c) alveoli and throat
(d) throat and larynx
Answer:
(b) alveoli of lungs

(ii) Blood consists of what fluid medium ? [1]
(a) Lymph
(b) Platelets
(c) Plasma
(d) All of these
Answer:
(c) Plasma

(iii) Rhythm of sleep in our body is controlled by? [1]
(a) Thymus gland
(b) Pineal gland
(c) ACTH
(d) ADH
Answer:
(b) Pineal gland

(iv) Damage of cerebellum will most affect the career of: [1]
(a) architect
(b) teacher
(c) librarian
(d) athlete
Answer:
(d) athlete

(v) A fuse wire is inserted in which wire ? [1]
(a) live wire
(b) in the neutral wire
(c) in the earth wire
(d) may be connected in any line
Answer:
(a) live wire

(vi) The resistivity of a certain material is 0.6 Ω m. The material is most likely to be: [1]
(a) an insulator
(b) a super conductor
(c) a conductor
(d) a semiconductor
Answer:
(d) a semiconductor

(vii) In optics an object which has higher refractive index is called : [1]
(a) optically rarer
(b) optically denser
(c) opitical density
(d) refractive index
Answer:
(b) optically denser

(viii) Image formed by plane mirror is : [1]
(a) real and erect
(b) real and inverted
(c) virtual and erect
(d) virtual and inverted
Answer:
(c) virtual and erect

(ix) Who stated the right hand thumb Rule? [1]
(a) Orsted
(b) Fleming
(c) Einstein
(d) Maxwell
Answer:
(d) Maxwell

(x) Rancidity can be prevented by [1]
(a) adding antioxidants
(b) storing food away from light
(c) keeping food in refrigerator
(d) all of these.
Answer:
(d) all of these.

(xi) Which one of the following will turn red litmus blue? [1]
(a) Vinegar
(b) Baking soda solution
(c) Lemon juice
(d) Soft drinks
Answer:
(b) Baking soda solution

(xii) Which among the following alloys contains non-metal as one of its constituents ? [1]
(a) Brass
(b) Amalgam
(c) Grun metal
(d) None of these
Answer:
(b) Amalgam

2. Fill in the blanks: (1 × 6 = 6)

(i) ………………………. protects spinal cord : [1]
Answer:
Vertebral column,

(ii) One molecule of glucose produces ………………………. ATP molecules. [1]
Answer:
38

(iii) …………………… is known as State tree of Rajasthan. [1]
Answer:
Khejari

(iv) ………………….. plan was started in 1985 to improve the quality of water in river Ganga. [1]
Answer:
Ganga Action

(v) When image is virtual, it is ………………….. [1]
Answer:
erect

(vi) The commercial unit of energy is …………………… [1]
Answer:
Kilowatt-hour

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

(i) What protects the trachea from being collapsed when there is no air in it ? [1]
Answer:
Cartilaginous rings

(ii) Accumulation of which substance oh darker side of stem causes bending of stem in uni-directional light ? [1]
Answer:
Auxins

(iii) What are the two main components of an ecosystem ? [1]
Answer:
Abiotic and biotic components

(iv) Make a list of forest produce that you use. [1]
Answer:
Wood for making furniture, doors, paper and fuel

(v) Mention any one negative effect of our affluent life style on the environment. [1]
Answer:
Chloro fluorocarbons used in refriger ators causing ozone hole

(vi) What is the other name of Joule/ Coulmb ? [1]
Answer:
Volt

(vii) What is a solenoid ? [1]
Answer:
It is a long helically wound coil of insulated copper wire

(viii) Which effect of electric current is utilized in the working of an electric fuse ? [1]
Answer:
An electric fuse works on the heating effect of current

(ix) Name the natural source of citric acid. [1]
Answer:
Lemon and orange

(x) Which bases are called alkalies ? [1]
Answer:
Soluble bases are called alkalies

(xi) Name two substances which can be used as olfactory indicators. [1]
Answer:
Onion and vanila

(xii) State the chemical properties on which the use of baking soda is based to make bread and cake soft and spongy. [1]
Answer:
It liberates CO₂ on heating which makes bread and cake soft and spongy

Part – B

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

Question 4.
What is transpiration? List its two functions. [2]
Answer:
The evaporation of water from the aerial parts of a plant is called transpiration.
Functions of Transpiration

1. It helps in the upward movement of water and minerals from root to the aerial parts through the stem and in their absorption.
2. It helps in cooling the plant surface.

Quetsion 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.
Define variation.
Answer:
Children do not resemble their parents completely. They possess characters obtained from both the parents. These changes in the phenotypic and genotypic characters are known as variations. Thus a given population of a species has indefinite variants.

Question 7.
Differentiate among primary, secondary and tertiary consumers. [2]
Answer:
Primary Consumers:
Herbivores which feed on plants form the second trophic level.
For example: Insects.

Secondary Consumers:
Carnivores which eat herbivores make the third trophic level.
For example: Frog.

Tertiary Consumers:
Top carnivores which feed on secondary consumers.
For example : Snake.

Question 8.
A ray of light, incident obliquely on a face of a rectangular glass slab placed in air, emerges from the opposite face parallel to the incident ray. State two factors on which the lateral displacement of the emergent ray depends. [2]
Answer:
Lateral displacement depends on the –

1. Angle of incidence
2. Thickness of slab
3. refractive index of the material.

Question 9.
What is meant by overloading of an electrical circuit ? [2]
Answer:
Overloading:
The current flowing in domestic wiring at a particular time depends on the power rating of the appliances being used if too many electrical appliances of high power rating are switched on at the same time, they draw extremely large quantity of current from ’ the circuit. This is known as the overloading of the circuit.

Question 10.
Find the resistance between points A and B in the circuit diagram given below: [2]

Answer:
R₂, R₃ and R₄ are in series and have resultant resistance R’ = 2 + 2 + 2 = 6Ω
R’ is in parallel combination with R₁.

∴ Resultant resistance of the circuit (R)
\(\frac{1}{R}=\frac{1}{R_{1}}+\frac{1}{R_{2}}\)
\(\frac{1}{6}+\frac{1}{6}\)
Resistance R = \(\frac{6}{2}\) = 3Ω

Question 11..
What is the basic difference between AC generator and DC generator ? [2]
Answer:
In AC generator, slip-ring type commutator is used and in DC generator split-ring type commutator is used. AC generator converts mechanical energy into electrical energy in form of alternating current. DC generator converts mechanical energy into electrical energy in the form of direct current.

Question 12.
Ammonium nitrate when heated disappears completely. Why? [2]
Answer:
Ammonium nitrate on heating decomposes into colourless gaseous products namely, water vapour and nitrous oxide.

Both products being gases, escape into the surroundings, leaving behind no visible products. Thus, it seems that ammonium nitrate has disappeared.

Question 13.
Write a balanced chemical equation for each of the following reactions and also classify them.
(a) Lead acetate solution is treated with dilute hydrochloric acid to form lead chloride and acetic acid solution.
(b) A piece of sodium metal is added to absolute ethanol to form sodium
ethoxide and hydrogen gas. [2]
Answer:
(a) (CH₃COO)₂ Pb + 2HCl → PbCl₂ + 2CH₃COOH; Double displacement reaction

(b) 2Na + 2C₂H₅OH → 2C₂H₅ONa + H₂; Displacement reaction

Question 14.
Write equations for the reactions of:
(i) iron with steam.
(ii) calcium and potassium with water. [2]
Answer:

(ii) 2K(s) + 2H₂O(l)
2KOH(aq) + H₂(g) + heat energy Ca(s) + 2H₂O(Z) Ca(OH)₂(aq) + H₂(g)

Question 15.
What would you observe when zinc is added to a solution of iron (II) sulphate ? Write the chemical reaction that takes place. [2]
Answer:
When zinc is added to a solution of iron (II) sulphate, iron gets precipitated. The light green colour of the solution fades away. The chemical reaction will be:

Question 16.
(i) Write the electron-dot structures for (a) sodium, (b) oxygen and (c) magnesium.
(ii) Show the formation of Na20 and MgO by the transfer of electrons. [2]
Answer:
(i) The representation of elements with valence electrons as dots and crosses around the elements is referred to as electron-dot structure for elements.
(a) Sodium (2, 8, 1) – Na^.
(b) Oxygen (2, 6)
(c) Magnesium, (2, 8, 2) = : Mg

Part – C

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

Question 17.
Explain the mechanism of opening and closing of stomata with diagrams. [3]
OR
How do the leaves of plants help in excretion? Explain briefly. [3]
Answer:

Mechanism of opening and closing of stomata:
The leaves have tiny apertures called stomata. Therefore, diffusion occurs through stomata in the leaves. Green leaves produce plenty of oxygen during day time in the process of photosynthesis. This oxygen is directly used by the leaf cells. At night oxygen diffuses into leaves through the stomata. The rate of photosynthesis is many times higher than the rate of respiration. Therefore, during day time surplus oxygen is given out by plants. Carbon dioxide is used in photosynthesis.

(OR)

During night plants diffuse out carbon dioxide. Oxygen may dissolve in water present around the cells of leaves and diffuses in across their cell walls and membranes. Intercellular spaces help in diffusion. Therefore, there are two main steps of urine formation, Alteration of blood, and re-absorption of useful substances. After reabsorption, only urea, uric acid, some unwanted salts and some amount of water is left beind in the tubule.

This liquid forms urine: From the kidney it is taken to bladder. It is stored for sometime in urinary bladder and then passed out of the body through urethra. Urine is slightly acidic, pale coloured liquid which contains water, urea, uric acid and some salts. Normally in an adult human the initial filtrate in the kidneys is about 180 litres daily. However the urine output is 1.5 to 2 litres a day because the remaining filtrate is reabsorbed in the kidney tubule.

Question 18.
What is meant by solenoid? How does a current-carrying solenoid behave? Give its main use. 3
OR
Describe an activity to show that the magnetic field lines are produced when current is passed through the circular coil. [3]
Answer:
Solenoid : A Coil of many circular turns of insulated copper wire wound on a cylindrical insulating body (i.e. cardboard etc.) such that its length is greater than its diameter is called a solenoid

When current is flowing through the solenoid, the magnetic field line pattern resembles exactly with those of a bar magnet with fixed polarity, i. e., North and South pole at its ends and it acquires the directive and attractive properties similar to bar magnet. Hence, the current carrying solenoid behaves as a bar magnet.

Use of current-carrying solenoid : It is used to form a temporary magnet called electromagnet as well as permanent magnet.

Question 19.
What are fossils ? Describe briefly two methods of determining the age of fossils. [3]
OR
What are homologous structures ? Give an example. Is it necessary that homologous structures always have a common ancestor? Justify your answer. [3]
Answer:
The remains or the preserved traces of living organisms of geological past are called fossils:

• When organisms die, their dead bodies decompose and get lost.
• But some parts of the body may be in the environment that does not let it decompose.

For example, dead insect will not decompose in hot mud, it will retain the impression of the insect body parts and thus preserved as fossils.

The age of fossils can be determined by two ways:

1. If we dig into the earth and strart finding fossils, it can be assume that the fossils closer to the surface are more recent to those found in deeper layers.
2. By detecting the ratios of different isotopes of the same element in the fossil material.

Question 20.
(a) What happens when an aqueous solution of sodium sulphate reacts with an aqueous solution of barium chloride ? State the physical condition of reactants in which reaction between them will not take place. Write the balanced chemical equation for the reaction and also mention the type of reaction.
(b) What changes in the colour of iron nails and copper sulphate solution do you observe after keeping the iron nails in copper sulphate solution for about half an hour ? [3]
OR
A silvery-white metal X taken in the form of ribbon when ignited, burr’ n air with a dazzling white flame to form a white powder Y. When water is added to powdei; Y, it dissolves partially to form another substance Z.
(a) What could metal X be ?
(b) What is powder Y ?
(c) With which substance metal X combines to form powder Y ?
(d) What is substance Z ? Name one domestic use of substance Z. [3]
Answer:
(a) When barium chloride solution is added to sodium sulphate solution, then a white precipitate of barium sulphate is formed along with sodium chloride solution:

Reaction will not take place if the reactants are in a solid state.

(b) When iron nails are dipped in Copper sulphate solution, then Iron sulphate solution and Copper metal are formed.

Part – D

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

Question 21.
(i) Describe double circulation in human being. Why is it necessary ?
(ii) Draw a diagram to show course of circulation in heart [4]
OR
(i) How are the alveoli designed to maximise the exchange of gases?
(ii) What would be the consequences of deficiency of haemoglobin in our body? [4]
Answer:
When the blood flows twice through the heart in each cardiac cycle (each course of . circulation) it is called double circulation. Deoxygenated blood from the body is brought to right atrium through great
veins. From right atrium blood is sent to right ventricle and from here it is pumped to lungs for purification.

The oxygenated blood is carried to left atrium. From the left atrium blood moves to left ventricle. Left ventricle pumps this blood to all body parts through aorta. As blood flows twice through the heart in one complete cycle it is called double circulation.

Significance-It keeps the oxygenated and deoxygenated blood separated and does not allow their mixing. Such a separation allows a highly efficient supply of oxygen to all body cells. This is specially required in organisms having high metabolic rate. Birds and mamma1s, including human being are warm blooded animals. To keep their body temperature constant their energy requirements are ligh,
so they need double circulation.

Question 22.
(a) Draw a ray diagram to show the formation of image of an object placed between infinity and the optical centre of a concave lens.
(b) A concave lens of focal length 15 cm forms an image 10 cm from the lens. Calculate:
(i) the distance of the object from the lens.
(ii) the magnification for the image formed. [4]
OR
(a) Under what condition will a glass lens placed in a transparent liquid become invisible ?
(b) Describe and illustrate with diagram, how we should arrange two
converging lenses so that a parallel beam of light entering one lens emerges as a parallel beam after passing through the second lens : [4]
Answer:
(a) Image formation when the object is at any position between infinity and optical centre.
Position of image: Between and optical centre.
Nature of image : Virtual,
erect and diminished.
(b) f = -155cm, v = – 10cm

(i) Using = \(\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\), we get
\(\frac{1}{u}=\frac{1}{v}-\frac{1}{f}\)
\(\frac{1}{-10}-\frac{1}{-15}\)
= \(\frac{1}{u}=\frac{-1}{30}\)
∴ u = -30cm
Therefore, the object is at 30 cm from the concave lens on its left side
(ii)
m = \(\frac{-10}{-30}=\frac{1}{3}\)

Question 23.
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. Name any two forms in which calcium carbonate is found in nature. 4
OR
(a) Mention the pH range whithin which our body works. Explain how antacids give relief from acidity. Write the name of one such antacid.
(b) Fresh milk has a pH of 6. How does the pH change as it turns to curd ?
Explain your answer. [4]
Answer:
Aim : To show acid reacts with metal carbonate to liberate carbon dioxide. Material required-CaCO₃
(marble chips), woulfe-bottle, thistle funnel, dil HC1, gas jar, matchbox, delivery tube bent at two right angles, lime water.
Procedure

1. Take marble chips in a woulfe- bottle
2. Add dil. HCl with the help of thistle funnel.
3. Collect the gas in gas jar by upward displacement of air.
4. Bring a burning matchstick near the gas jar and record your observations.

Observation:
The burning matchstick will get extinguished because carbon dioxide is neither combustible nor supporter of combustion. Lime water will turn milky due to fomation of insoluble calcium carbopate. It can be used as a test for C02. The chemical reactions taking place are as follows :