Class 10th CBSE students, this is the most important time for your academics as the board exams are already going on. Here are some important questions of science which you should not skip. Prepare all yours questions with your tuition teachers, School Teachers or your Home Tutors. It will be more beneficial for you if you have hired a home tutor in your academic sessions. The following questions are the most important :-
1. A metal X is used in thermite process. When X is burnt in air it gives an amphoteric oxide Y. X and Y are respectively:
a.Fe and Fe2O3
b.Al and Al2O3
c.Fe and Fe3O4
d.Al and Al3O4
2.Select washing soda from the following:
a.NaHCO3
b.Na2CO3⋅5H2O
c.Na2CO3⋅10H2O
d.NaOH
3.If four identical resistors, of resistance 8 ohm, are first connected in series so as to give an effective resistance Rs, and then connected in parallel so as to give an effective resistance Rp, then the ratio Rs/Rp is
a.32
b.2
c.0.5
d.16
4.n domestic electric circuits the wiring with 15 A current rating is for the electric devices which have
a.higher power ratings such as geyser.
b.lower power ratings such as fan.
c.metallic bodies and low power ratings.
d.non-metallic bodies and low power ratings.
5.Solid Calcium oxide reacts vigorously with water to form Calcium hydroxide accompanied by the liberation of heat. From the information given above it may be concluded that this reaction
a.is endothermic and pH of the solution formed is more than 7.
b.is exothermic and pH of the solution formed is 7.
c.is endothermic and pH of the solution formed is 7.
d.is exothermic and pH of the solution formed is more than 7.
6.Juice of tamarind turns blue litmus to red. It is because of the presence of an acid called:
a.methanoic acid
b.acetic acid
c.tartaric acid
d.oxalic acid
7.Which of the following statement(s) is (are) true about human heart?
- Right atrium receives oxygenated blood from lungs through pulmonary artery.
- Left atrium transfers oxygenated blood to left ventricle which sends it to various parts of the body.
- Right atrium receives deoxygenated blood through vena cava from upper and lower body.
- Left atrium transfers oxygenated blood to aorta which sends it to different parts of the body.
a.(a)
b.(a) and (d)
c.(b) and (c)
d.(b) and (d)
8.Select out of the following a gland which does NOT occur as a pair in the human body:
a.Pituitary
b.Ovary
c.Testis
d.Adrenal
10.Identify the mode of asexual reproduction in the following organism:
a.Fragmentation
b.Multiple fission
c.Budding
d.Binary fission
11. A cross made between two pea plants produces 50% tall and 50% short pea plants. The gene combination of the parental pea plants must be
a.Tt and Tt
b.TT and Tt
c.Tt and tt
d.TT and tt
12. Study the I-V graph for three resistors of resistances R1, R2 and R3 and select the correct statement from the following:
a.R1 = R2 = R3
b.R1 > R2 > R3
c.R3 > R2 > R1
d.R2 > R3 > R1
13.Strength of magnetic field produced by a current carrying solenoid DOES NOT depend upon:
a.number of turns in the solenoid
b.direction of the current flowing through it
c.radius of solenoid
d.material of core of the solenoid
14.Select from the following a process in which a combination reaction is involved:
a.Black and White photography
b.Burning of coal
c.Burning of methane
d.Digestion of food
15. What is the maximum resistance which can be made using five resistors each of 15 Ω?
a.1/5 Ω
b.10 Ω
c.5 Ω
d.1
16.A metal ribbon X burns in oxygen with a dazzling white flame forming a white ash Y. The correct description of X, Y and the type of reaction is:
a.X = Ca; Y = CaO; Type of reaction = Decomposition
b.X = Mg; Y = MgO; Type of reaction = Combination
c.X = Al; Y = Al2O3; Type of reaction = Thermal decomposition
d.X = Zn; Y = ZnO; Type of reaction = Endothermic
.Q. No. 17 to 20 are Assertion – Reasoning based questions.
These consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below.
(a) Both (A) and (R) are true and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).
(c) (A) is true but (R) is false.
(d) (A) is false but (R) is true.
17.Assertion (A): A current carrying straight conductor experiences a force when placed perpendicular to the direction of magnetic field.
Reason (R): The net charge on a current carrying conductor is always zero.
a.Both A and R are true and R is the correct explanation of A.
b.Both A and R are true but R is not the correct explanation of A.
c.A is true but R is false.
d.A is false but R is true.
18.
Assertion (A): The inner walls of the small intestine have finger like projections called villi which are rich in blood.
Reason (R): These villi have a large surface area to help the small intestine in completing the digestion of food.
a.Both A and R are true and R is the correct explanation of A.
b.Both A and R are true but R is not the correct explanation of A.
c.A is true but R is false.
d.A is false but R is true.
19.
Assertion (A): In humans, if gene (B) is responsible for black eyes and gene (b) is responsible for brown eyes, then the colour of eyes of the progeny having gene combination Bb, bb or BB will be black only.
Reason (R):The black colour of the eyes is a dominant trait.
a.Both A and R are true and R is the correct explanation of A.
b.Both A and R are true but R is not the correct explanation of A.
c.A is true but R is false.
d.A is false but R is true.
20.Assertion (A): Reaction of Quicklime with water is an exothermic reaction.
Reason (R): Quicklime reacts vigorously with water releasing a large amount of heat.
a.Both A and R are true and R is the correct explanation of A.
b.Both A and R are true but R is not the correct explanation of A.
c.A is true but R is false.
d.A is false but R is true.
1.Name the type of chemical reaction in which calcium oxide reacts with water. Justify your answer by giving balanced chemical equation for the chemical reaction.
22.State one role of each of the following in human digestive system:
- Hydrochloric acid
- Villi
- Anal Sphincter
- Lipase
23.How is the movement of leaves of a sensitive plant different from the downward movement of the roots?
OR
There is a hormone which regulates carbohydrate, protein and fat metabolism in our body. Name the hormone and the gland which secretes it. Why is it important for us to have iodised salt in our diet?
24.
Study the experimental set-up shown in the diagram and write chemical equation for the chemical reaction involved. Name and define the type of reaction. List two other metals which can be used in place of iron to show the same type of reaction with copper sulphate solution.
25.Name the ore of mercury and state the form in which it is found in nature. Write the chemical equations along with the condition required for the reactions involved in the extraction of mercury from its ore.
26.An electric source can supply a charge of 500 coulomb. If the current drawn by a device is 25 mA, find the time in which the electric source will be discharged completely.
27.Mendel crossed pure tall pea plants (TT) with pure short pea plants (tt) and obtained F1 progeny. When the plants of F1 progeny were self-pollinated, plants of F2 progeny were obtained.
- What did the plants of F1 progeny look like? Give their gene combination.
- Why could the gene for shortness not be expressed in plants of F1 progeny?
- Write the ratio of the plants obtained in F2 progeny and state the conclusion that can be drawn from this experiment.
28.(i)What happens when a bundle of wires of soft iron is placed inside the coil of a solenoid carrying a steady current? Name the device obtained. Why is it called so?
(ii)Draw the magnetic field lines inside a current carrying solenoid. What does this pattern of magnetic field lines indicate?
29.(i)List any two contraceptive methods practised only by women. Mention how these methods work.
(ii)Write the two roles performed by testes in human males.
30. Use of pesticides to protect our crops affect organisms at various trophic levels especially human beings. Name the phenomenon involved and explain how does it happen.
31.Draw a labelled diagram to show electrolytic refining of copper. State what happens when electric current is passed through the electrolyte taken in this case.
32.Draw a diagram to show the pattern of magnetic field lines on a horizontal sheet of paper due to a straight conductor passing through its centre and carrying current vertically upwards. Mark on it (i) the direction of current in the conductor and (ii) the corresponding magnetic field lines. State right hand thumb rule and check whether the directions marked by you are in accordance with this rule or not.
33.Explain the process of transport of oxygenated and deoxygenated blood in a human body.
34.A saturated organic compound A belongs to the homologous series of alcohols.
On heating A with concentrated sulphuric acid at 443 K, it forms an unsaturated compound B with molecular mass 28 u.
The compound B on addition of one mole of hydrogen in the presence of Nickel, changes to a saturated hydrocarbon C.
- Identify A, B and C.
- Write the chemical equations showing the conversion of A into B.
- What happens when compound C undergoes combustion?
- State one industrial application of hydrogenation reaction.
- Name the products formed when compound A reacts with sodium.
35. (i)Name the two types of pollination and differentiate between them.
- Explain the post fertilization changes that occur in the ovary of a flower.
- Given below is a diagram of a germinating seed. Label the parts that
- gives rise to future shoot.
- gives rise to future root system.
- stores food.
37.Read the following text carefully and answer the questions that follow:
Human digestive system is a tube running from mouth to anus. Its main function is to breakdown complex molecules present in the food which cannot be absorbed as such into smaller molecules. These molecules are absorbed across the walls of the tube and the absorbed food reaches each and every cell of the body where it is utilised for obtaining energy.
- Name the glands present in the buccal cavity and write the components of food on which the secretion of these glands act upon. (1)
- Two organs have a sphincter muscle at their exit. Name them. (1)
- What will happen if:(2)
- mucus is not secreted by the gastric glands.
- Villi are absent in the small intestine.
OR
Bile juice does not contain any enzyme, yet it has important roles in digestion. Justify the statement. (2)
38. A highly polished surface such as a mirror reflects most of the light falling on it. In our daily life we use two types of mirrors plane and spherical. The reflecting surface of a spherical mirrors may be curved inwards or outwards. In concave mirrors, reflection takes place from the inner surface, while in convex mirrors reflection takes place from the outer surface.
- Define the principal axis of a concave mirror. (1)
- A ray of light is incident on a concave mirror, parallel to its principal axis. If this ray after reflection from the mirror passes through the principal axis from a point at a distance of 10 cm from the pole of the mirror, find the radius of curvature of the mirror. (1)
- An object is placed at a distance of 10 cm from the pole of a convex mirror of focal length 15 cm. Find the position of the image. (2)
OR
A mirror forms a virtual, erect and diminished image of an object. Identify the type of this mirror. Draw a ray diagram to show the image formation in this case.
39.The teacher while conducting practicals in the laboratory divided the students into three groups and gave them various solutions to find out their pH and classify them into acidic, basic and neutral solutions.
Group A – Lemon juice, vinegar, colourless aerated drink
Group B – Tomato juice, coffee, ginger juice
Group C – Sodium hydroxide, sodium chloride, lime water
(i)For the solutions provided, which group is/are likely to have pH value (i) less than 7, and (ii) greater than 7?
(ii)List two ways of determining pH of a solution.
(iii)Explain, why the sour substances such as lemon juice are effective in cleaning the tarnished copper vessels.
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