SAMPLE QUESTION PAPER
Class – X
Session: 2021-22 (TERM II) Time Allowed: 120 minutes
Subject: Science Maximum Marks: 40
General Instructions:
1. All questions are compulsory.
2. The question paper has three sections and 15 questions. All questions are compulsory.
3. 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.
4. Internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions.
SECTION A
1. Some of the elements and their atomic numbers are given in the table.
i) How many valence electrons are there in the element R?
Ans. Electronic configuration of R is:
Thus, there are 3 valence electrons in element R.
ii) Write the chemical formula formed by combining the elements Q and S.
Ans. Q has 1 electron and S has 7 electrons in the valence shell. Therefore, formula of the compound will be QS.
2. What are the two properties of carbon which lead to a huge number of carbon compounds we see around us?
Ans. Two properties are:
i) Catenation: the ability to form bonds with other atoms of carbon.
ii) Tetravalency of carbon.
OR
Write the molecular formula of the second member of the alkene series and draw the structure of first member.
Ans. Second member of the alkene series:
General formula: CnH2n
As the formula CH2 does not exist C2H4 is the first member of alkene series.
So second member – C3H6 (Propene)
Structure of the first member:
3. i) How is binary fission different from multiple fission?
| Binary fission | Multiple fission |
| The organism splits into two nuclei (daughter cells) Eg. Amoeba | The organism splits into many nuclei (daughter cells). Eg Plasmodium. |
ii) State the reason why testes are located outside the abdominal cavity?
Ans. a) Sperm formation requires a lower temperature than normal body temperature.
b) This temperature is 1-30C lower than the body temperature.
OR
Label the following parts in the given diagram of the longitudinal section of a flower.
Ovary, Petals, Anther, Sepals
4. Show the cross breeding of tall pea plants (Tt)(heterozygous) with dwarf pea plants (tt)(homozygous) and write the phenotypic ratio of F1 generation.
5. i) What is the principle on which electric motor is based upon?
Ans. Principle of electric motor: A current carrying conductor experiences a force when placed in a magnetic field. If the direction of magnetic field and that of current are mutually perpendicular, then the direction of force is given by Fleming’s left hand rule.
ii) Suppose a current-carrying solenoid coil is suspended freely. In which direction will it settle and why?
Ans. In north – south direction.
Because it behaves as a bar magnet.
6. What will happen if we kill all the herbivores in a food chain?
Ans. If we kill all the herbivores of a food chain,
- The number of individuals in the next trophic level (secondary consumers) will decrease due to non-availability of food.
- Also, the number of individuals in the first trophic level (producers) will increase because there is no one to eat them. (imbalance in the ecosystem)
OR
How does improper disposal of biodegradable substances would affect the environment? (any two ways)
Ans.
- They would serve as breeding ground for flies and mosquitoes which are carriers of diseases like Cholera, typhoid and malaria.
- It will produce foul smell, thus causing air pollution. If thrown to water, it would cause water pollution.
7. In the given figure identify the organs concerned with
i) Production of egg
ii) Site of fertilization
iii) Site of implantation
iv) Site of entry of sperm
Ans.
SECTION – B
8. i) Write the formula of Cyclopentane.
Ans. Formula of Cyclopentane: C5H10
Formula of Propane: C3H8
ii) What will be the formula and electron dot structure of Propane?
Ans.
Electron dot structure of Propane (C3H8):
9. Can following group of elements be classified as Dobereiner’s triad?
i) Na, Si, Cl
Ans. No, because all these elements do not have similar properties although the atomic mass of Silicon is average of the atomic masses of Sodium (Na) and Chlorine (Cl).
ii) Be, Mg, Ca
Atomic masses of Be (9), Na (23), Mg (24), Si (28), Cl (35), Ca (40. Explain by giving reason.
Ans. Yes, because these elements have similar properties and the atomic mass of Magnesium (Mg) is approximately average of the atomic masses of Be and Ca.
OR
How many groups and periods are there in the modern periodic table of elements? In modern periodic table how do the atomic size and metallic character of elements vary as we move from:
i) Top to bottom in a group
Ans. There are 18 groups and 7 periods in the modern periodic table.
On moving down a group, the atomic size increases and metallic character also increases.
ii) Left to right in a period.
Ans. On moving from left to right in a period, the atomic size decreases and metallic character also decreases.
10. i) What happens to the pollen grains of a flower when it is transferred to the stigma of same flower or the other flower of the same species? Explain the whole process.
Ans.
- Pollen grows the pollen tube so as to reach the female gamete in the ovary.
- The pollen tube carries two male gametes in it.
- One male gamete fuses with egg cell and forms zygote
- The other male gamete fuses with secondary nucleus to form endosperm nuclei.
ii) State the difference between budding in Hydra and budding in Yeast.
| Budding in Hydra | Budding in Yeast |
| 1) Beds produced are multicellular | 1) Buds produced are unicellular. |
| 2) Buds get detached from parent body soon. | 2) Buds may remain attached to the parent body. |
11. Find out the following in the electric circuit given in the figure,
i) Current flowing through 4 Ω resistor
Ans. Current flowing through 4 Ω resistor:
1/Rp = 1/8 + 1/8
= 2/8 = 4 Ω
Rs 4 Ω + Rp = 4 Ω + 4 Ω = 8 Ω
So current flowing through 4 Ω = V/I
= 8V/8 Ω = 1 A
ii) Potential difference across 4 Ω resistance.
Ans. Potential difference across 4 Ω:
V = RI
= 4 x 1
= 4V
12. What is biological magnification? If the concentration of DDT is 0.2 ppm in the water of a lake which organism will show maximum concentration of DDT in the given food chain? Give reason to your answer.
Algae, Zooplanktons, Small Fish, Big Fish
Ans. The process of increase of concentration of harmful chemicals like pesticides from first trophic level to the last trophic level in a food chain is called Biological magnification.
- The concentration of DDT will be maximum in Big fish as accumulation of non-biodegradable substance is maximum at highest trophic level.
Algae — > Zooplanktons — > Small fish — > Big fish
- DDT is metabolized and excreted much more slowly than the nutrients that are passed from one trophic level to the next. So DDT accumulates in the bodies of animals.
13. i) Define resistance? Write its SI unit.
Ans. resistance is a property of conductor due to which it resists the flow of electric current thorugh it. Its SI unit is ohm (Ω)
ii) State Joule’s law of heating.
Ans. Heat produced in a resistor is –
- Directly proportional to square of current flowing through it.
- Directly proportional to resistance
- Directly proportional to time
H = I2Rt = VIt = V2t/R
OR
Explain the following:
i) Why is the tungsten used exclusively for filament of electric lamps?
Ans. Tungsten is used for filament of electric lamps because its melting point is extremely high.
ii) How does the resistance of a wire vary with its area of cross-section?
Ans. Resistance (R) of a wire is inversely proportional to its cross-section area (A)
iii) Why are series arrangements not used for domestic circuits?
Ans. Series arrangements cannot be used for domestic circuits because
- In series arrangement, same current will flow through all the appliances, which is not required
- We cannot use independent on/off switches with individual appliances
- Total resistance of domestic circuit will be the sum of the resistances of all the appliances and so current drawn by the circuit will be less.
SECTION – C
14. In a monohybrid cross between tall pea plants denoted by TT and short pea plants dented by tt, Sanju obtained only tall plants denoted by Tt in the F1 generation. However, in F2 generation he obtained both tall and short plants. Now answer these questions:
i) Which are dominant and recessive characters in this experiment.
Ans. Dominant trait
Recessive trait
ii) What are the phenotypic and genotypic ration in F2 generation.
3:1
1:2:1
iii) Explain how many dominant and recessive traits will be produced in the progeny of F2?
1 part Homozygous Tall : 2 parts Heterozygous Tall : 1 part Homozygous dwarf
OR
What were the specific observations Mendel noticed in the monohybrid and dihybrid crosses?
Ans. Observations noticed by Mendel in his experiments with Monohybrid and Dihybrid crosses were:
- In Monohybrid crosses the dominant allele of a trait are seen (law of dominance)
- In Dihybrid crosses segregation of traits in the offspring were seen (law of Independent Assortment)
15. A student fixes a sheet of white paper on a drawing board. He places a bar magnet in the centre of it. He sprinkles some iron fillings uniformly around the bar magnet. Then he taps the board gently and observes that the iron fillings arrange themselves in a particular pattern. Now answer the following questions:
i) Why do iron fillings arrange in such a pattern?
Ans. the iron fillings experiences force due to the magnetic field and thus align themselves along the magnetic field lines.
ii) What do the lines along which the iron fillings align represent?
Ans. The lines along which the iron fillings align represent the magnetic field lines.
iii) What does the crowding of the iron fillings at the ends of the magnet indicate?
Ans. a) The crowding of the iron fillings at the ends of the magnet indicate position of two magnetic poles of N and S of bar magnet.
b) It also indicates that the strength is maximum at poles (where it is crowded)
OR
Write any two properties of magnetic fields lines.
Ans. Two properties of magnetic fields lines are:
- A magnetic field line always points in the direction of magnetic field
- No two magnetic field lines intersect each other.