Students can access the CBSE Sample Papers for Class 10 Science with Solutions and marking scheme Term 2 Set 7 will help students in understanding the difficulty level of the exam.
CBSE Sample Papers for Class 10 Science Term 2 Set 7 with Solutions
Time : 2 Hours
Max. Marks : 40
General Instructions :
- All questions are compulsory.
- The question paper has three sections and 15 questions. All questions are compulsory.
- Section-A has 7 questions of 2 marks each; Section-B has 6 questions of 3 marks each; and Section-C has 2 case based questions of 4 marks each.
- Internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.
Section – A
Question 1.
In the following food chain, grass provides 4000 J of energy to the grasshopper.
Grass, grasshopper, frogs, snakes.
How much energy will be available to snakes and frogs?
OR
The first trophic level in a food chain is always a green plant. Why? (2)
Answer:
According to Lindeman’s 10 per cent law, 40 J of energy will be available to frogs and 4 J of energy will be avoilable to snakes.
OR
Green plants are the producers which prepare their own food by utilising solar energy from inorganic sources and all other living organisms depends on them for food. Herbivores and carnivores depend upon green plants either directly or indirectly for food. Hence, the first trophic level in a food chain is always a green plant.
Question 2.
Answer the following questions: (2)
(a) Explain why, the properties of elements are repeated after 2, 8, 18 and 32 elements in the periodic table.
(b) What are the advantages of the periodic table?
OR
Which of the given elements A, B, C, D and E with atomic number 2, 3, 7,10 and 30 respectively belong to the same period?
Answer:
(a) The properties of elements are repeated after 2, 8, 18 and 32 elements in the periodic table because
the electronic configurations of the elements are repeated in this manner.
(b) Advantages of the periodic table are:
- It is easier to remember the properties of an element if its position in the periodic table is known.
- The type of compounds formed by an element can be predicted by knowing its position in the periodic table.
OR
The first period contains 2 elements. Whereas, both second and third period contains 8 elements. Therefore, the first period contains 1 to 2 atomic number. The second period contains 3 to 10 atomic number. The third period contains 11 to 18 atomic number. The fourth period contains 19 to 36 atomic number. Therefore, B, C and D belong to the same period.
Question 3.
What is the role of a split ring in an electric motor? (2)
OR
(a) What is the shape of a current-carrying conductor whose magnetic field pattern resembles that of a bar magnet?
(b) What is the principle of an electric motor?
Answer:
In an electric motor, after every half rotation the direction of coil gets reversed due to change in orientation of the magnetic field. To ensure a continuous rotation; a split ring is attached to the coil so that the polarity of the coil changes after every half rotation. This changes the direction of current and thus the armature keeps on rotating continuously.
OR
(a) A solenoid
(b) Electric motor works on the principle of magnetic effect of current.
Question 4.
All the variations in a species do not have equal chances of survival. Why? (2)
Answer:
According to ‘Survival of the fittest’, only the species which can adapt themselves to the environment can survive. Selection of the variants occurs by the different environmental factors. This forms the basis for evolution. Also, when a new change or variation occurs it means that the DNA constitution and the bodily cell apparatus also undergo genetic changes which result in the formation of a new variant. However, this change in the DNA might not be able to survive in the new environment. So, the DNA may get damaged and may stop functioning regularly which will affect the survival of the variant. The variations or the changes that are helpful and help in the evolution of the species will survive while the others will perish.
Question 5.
Write the name and formula of the 2nd member of homologous series having general formula \(\mathrm{C}_{n} \mathrm{H}_{2 n}\). (2)
Answer:
CnH2n : Alkene
2nd member is propene (C3H6)
Question 6.
(a) What factors could lead to the rise of a new species?
(b) A Mendelian experiment consisted of breeding pea plants bearing violet flowers with pea plant bearing white flowers. What will be the result in F1 progeny? (2)
Answer:
(a) The factors that could lead to the rise of a new species are genetic variations, genetic drift, reproductive isolation and natural selection.
(b) All the progeny of F1 generation will have violet flowers because violet colour is dominant over the recessive white colour.
Question 7.
How does binary fission differ from multiple fission? (2)
Answer:
Binary fission | Multiple fission |
1. A single parent cell divides into two daughter cells. | It results in production of many daughter cells. |
2. Nucleus divides once and then each nucleus gets surrounded by cytoplasm to form two individuals. | Nucleus divides repeatedly to form many nuclei and each gets surrounded by cytoplasm to form many daughter cells. |
3. If occurs under favourable conditions. Example: Binary fission in Amoeba, Paramecium. | It occurs under unfavourable conditions. Example: Plasmodium. |
Section – B
Question 8.
Rajeev, a sales executive in a MNC was not keeping well for a long time. He underwent a complete medical check-up and was diagnosed as HIV+. He was terminated on account of this condition. (3)
(a) To which category of disease does AIDS belong to? Give its causative organism.
(b) Do you think it was a right decision by the head of the company? Justify.
(c) What concern should the society show towards HIV+ individuals?
Answer:
(a) AIDS is a sexually transmitted disease. Its causative organism is HIV.
(b) No, it was not a right decision by the head of the company because HIV is not spread by shaking hands, mixing with HIV infected individuals. Instead he should be given equal rights, justice and freedom so that he should feel happy and should not get depressed.
(c) The society should show positive attitude towards HIV positive persons. They should be given proper care and treatment. Everybody should support them so that they can lead a healthy life without getting mental depression. We should not isolate them but we should provide proper education and create awareness among people about HIV and AIDS.
Question 9.
What is a food web? Give few characteristics of a food web? Give an example of a food web? (3)
OR
List five points of difference between producers and consumers?
Answer:
Food web is a network of food chains which become interconnected at various trophic levels so as to
form a number of feeding connections amongst different organisms of a biotic community.
Some characteristics of a food web are:
- Food web is an interlink of different food chains.
- It provides alternative pathways of food availability.
- Due to greater alternatives for food, it makes the ecosystem stable.
- It helps in development of an ecosystem.
Example of food web:
Or
Producers | Consumers |
1. They prepare their own food. | They depend on producers for their food. |
2. They prepare food from inorganic material by the process of photosynthesis. | They depend on readymade food. |
3. They always constitute the first trophic level. | They are placed at second or higher trophic levels. |
4. They possess chlorophyll which helps them in synthesising their own food. | They do not possess chlorophyll pigments. |
5. They have the capacity to trap solar energy and convert them to chemical energy in the form of carbohydrates. Example – Green plants, algae etc. | They cannot trap solar energy and convert to chemical energy. They eat producers to get chemical energy. Example – Humans, other animals like goat, rabbit, lion, tiger etc. |
Question 10.
Answer the following questions: (3)
(a) How an electric motor works?
(b) What is the role of a split ring in an electric motor?
(c) Define magnetism.
Answer:
(a) When a rectangular coil is placed in a magnetic field and current is passed through it, a force acts on the coil which rotates it continuously. Thus, when the coil rotates, the shaft attached to it also rotates converting the electrical energy supplied to the motor to the mechanical energy of rotation.
(b) In an electric motor, after every half rotation the direction of coil gets reversed due to change in orientation of the magnetic field. To ensure a continuous rotation; a split ring is attached to the coil so that the polarity of the coil changes after every half rotation. This changes the direction of current and thus the armature keeps on rotating continuously.
(c) The property by virtue of which a magnet attracts certain metals such as iron, cobalt, nickel etc., is termed as magnetism.
Question 11.
The elements of the third period of the Periodic Table are given below: (3)
Group → | I | II | III | IV | V | VI | VII |
Period ↓ 3 |
Na | Mg | Al | Si | P | S | CL |
(a) Which atom is bigger, Na or Mg? Why?
(b) Identify the most (i) metallic and (ii) non-metallic element in Period 3.
(c) Which is more non-metallic, S or Cl?
OR
(a) Why do we classify elements?
(b) What were the two criteria used by Mendeleev in creating his Periodic Table?
(c) Why did Mendeleev leave some gaps in his Periodic Table?
Answer:
(a) Na is bigger than Mg because on moving from left to right in a period, the atomic number of elements increases which means that the number of protons and electrons in the atom increases and the nuclear charge also increases. The increase in the nuclear charge pulls or attracts valence electrons at the centre more efficiently and thus the atomic size decreases.
(b) (i) Most metallic element is Na.
(ii) Most non-metallic element is Cl;
This is because on moving from left to right in a period the nuclear charge increases thus the valence electrons are pulled in more strongly by the nucleus and it becomes more and more difficult for the atoms to lose electrons so, tendency of atoms to lose electrons (i.e., metallic character) decreases on moving from left to right in a period.
On the other hand, due to increased nuclear charge, it becomes easier for the atoms to gain electrons. So the tendency to gain electrons (i.e., non-metallic character) increases on moving than left to right in a period.
Cl is more non-metallic than S because on moving from left to right in a period, nuclear charge increases so the tendency to gain electrons increases (i.e., non-metallic character).
OR
(a) As different elements were being discovered, scientists gathered more information about the properties of these element and it was observed that it was difficult to organise all the information or properties of these elements. So, scientists started discovering some pattern in their properties to classify all the known elements to make their study easier.
(b) Atomic mass and similarity of chemical properties were the two criteria used by Mendeleev in his Periodic Table.
(c) Mendeleev left some gaps in his Periodic Table as he predicted the existence of some elements that had not been discovered at that time.
Question 12.
State the following: (3)
(a) Two properties of carbon which lead to the formation of a large number of carbon compounds.
(b) Write the next homologue of C2H4 and C4H6.
(c) Write the name and molecular formula of the first member of the homologous series of alkyne.
(d) Write the next two members of homologous series for C2H6 and C3H8?
(e) Write the name and formula of second member of homologous series having general formula (\(\mathrm{C}_{n} \mathrm{H}_{2 n}\)).
(f) Write the name and formula of second member of homologous series having general formula (\(\mathrm{C}_{n} \mathrm{H}_{2 n-2}\)).
Answer:
(a) Catenation and tetravalency.
(b) C3H6 and C5H8
(c) Ethyne (C2H2)
(d) C4H10 and C5H12
(e) Propene (C3H6)
(f) Propyne (C3H4)
Question 13.
How can three resistors of resistances 2 Ω, 3 Ω and 6 Ω be connected to give a total resistance of : (3)
(a) 4 Ω (b) Ω?
Answer:
The three resistors of resistances 2 Ω, 3 Ω and 6 Ω have to be combined as shown in the figure to obtain 4 Ω resistance.
Equivalent resistance of 3 Ω and 6 Ω connected in parallel is,
Now Rp and 2 Ω are joined in series and the equivalent resistance is,
R = Rp + 2 = (2 + 2) Ω
= 4 Ω
In order to obtain 1 Ω resistance, the resistors, 2 0,30 and 6 Ω have to be combined as shown in figure. 2 0,3W and 6 Ω resistances are connected in parallel.
Section – C
This section has 02 case-based questions (14 and 15). Each case is followed by 03 sub-questions (a, b and c). Parts a and b are compulsory. However, an internal choice has been provided in part c.
Question 14.
Mrs. Joshi, an eight months pregnant lady was suggested by her doctor to get an ultrasound done.She went to a radiologist with her husband and got the ultrasound done. When the ultrasound was done, her husband asked doctor about the sex of the baby in the womb. (4)
(a) Is it ethical to determine the sex of the foetus? Why?
(b) What is the chance of giving birth to a girl child in human beings?
(c) What has government done to stop female foeticides?
OR
Ram met with an accident. John his school mate takes him to the hospital where Ram (AB blood group) needs blood transfusion. John also has AB blood group and is willing to donate his blood but Ram’s mother object by saying “John belongs to different community so has different type of blood”. Give your opinion about Ram’s mother views.
Answer:
(a) No, it is not ethical to determine the sex of the foetus because sex determination may lead to female foeticides which results in death of a girl child and thus the sex ratio becomes unbalanced in a society.
(b) The chance of giving birth to a girl child in human beings is 50%.
(c) Government has imposed a ban on sex determination techniques to stop female foeticides.
OR
Blood group does not depend on community, same blood group is same for all communties. Blood group AB has two alleles A and B in the people of all communities.
Question 15.
(a) Why is a series arrangement not used for domestic circuits?
(b) (i) Two wires P and Q are made of copper. The wire P is long and thin, while the wire Q is short
and thick. Which will have more specific resistance? Give a reason for your answer.
(ii) Why should a connection wire be thick?
(c) Name a material which is used for making standard resistors. Give a reason for your answer. (4)
OR
Answer the following questions:
(i) List the factors on which the resistance of a conductor in the shape of wire depends.
(ii) Why are metals good conductors of electricity whereas glass is a bad conductor of electricity? Give reason.
Answer:
(a) Series arrangement is not used for domestic circuits for the following reasons:
- The voltage of the source gets divided in all the appliances connected in series, in the ratio of their resistances, so each appliance does not operate at its rated voltage.
- The resistance of the circuit increases and it reduces the current in the circuit, so each appliance gets less power.
- If any one appliance in series arrangement is switched off (or gets spoilt), no other appliance connected with it in series will then operate.
(b) (i) Both the wires will have same specific resistance, since they are both made of same material (i.e., copper) and there is no change in temperature.
(ii) Resistance of a wire is inversely proportional to its area of cross-section (or thickness). Hence, a connection wire should be thick to reduce its resistance.
(c) Standard resistors are made from alloys such as constantan, manganin etc., because they have high specific resistance and the effect of change in temperature on their resistance is negligible.
OR
(i) Resistance of a conductor depends directly on its length and is inversely proportional to the area of cross-section.
(ii) Metals have free electrons and they move and conduct electricity, whereas glass does not have free electrons and charges to flow as it is an insulator.