Science Delhi Set 3 2015-2016 English Medium Class 10 Question Paper Solution

Select saturated hydrocarbons from the following: C₃H₆; C₅H₁₀; C₄H₁₀; C₆H₁₄; C₂H₄

What happens when a Planaria gets cut into two pieces?

Why are green plants called producers?

Define the power of a lens.

What does sign of power (+ve or –ve) indicate?

State power of a lens S.I. unit.

How unit of power related to focal length of a lens?

List four advantages of properly managed watershed management.

Out of the two-reuse and recycle-which, in your opinion, is better to practise? Give reason.

Name the compound formed when ethanol is heated in excess of conc. sulphuric acid at 443 K. Also, write the chemical equation of the reaction stating the role of conc. sulphuric acid in it. What would happen if hydrogen is added to the product of this reaction in the presence of a catalyst such as palladium or nickel?

When ethanol reacts with ethanoic acid in the presence of conc. H₂SO₄, a substance with fruity smell is produced. Answer the following:-

(i) State the class of compounds to which the fruity smelling compounds belong. Write the chemical equation for the reaction and write the chemical name of the product formed.

(ii) State the role of conc. H₂SO₄ in the reaction.

Two elements ‘A’ and ‘B’ belong to the 3^rd period of Modern periodic table and are in group 2 and 13, respectively. Compare their following characteristics in tabular form:-

(a) Number of electrons in their atoms

(b) Size of their atoms

(c) Their tendencies to lose electrons

(d) The formula of their oxides

(e) Their metallic character

(f) The formula of their chlorides

An element 'M' with electronic configuration (2, 8, 2) combines separately with (NO₃)^–, (SO₄)^2– and (PO₄)^3– radicals. Write the formula of the three compounds so formed. To which group and period of the Modern Periodic Table does the element 'M' belong? Will 'M' form covalent or ionic compounds? Give reason to justify your answer.

Answer the following question.

What is pollination? Explain the different types of pollination.

Name and differentiate between the two modes of pollination in flowering plants.

Suggest three contraceptive methods to control the size of human population, which is essential for the health and prosperity of a country. State the basic principle involved in each.

Name the parts A, B and C shown in the following diagram and state one function of each.

In a monohybrid cross between tall pea plants (TT) and short pea plants (tt), a scientist obtained only tall pea plants (Tt) in the F₁ generation. However, on selfing the F₁ generation pea plants, he obtained both tall and short plants in F₂ generation. On the basis of above observations with other angiosperms also, can the scientist arrive at a law? If yes, explain the law. If not, give justification for your answer.

List three distinguishing features, in tabular form, between acquired traits and the inherited traits.

Draw a ray diagram to show the refraction of light through a glass slab and mark angle of refraction and the lateral shift suffered by the ray of light while passing through the slab.

If the refractive index of glass for light going from air to glass is 3/2, find the refractive index of air for light going from glass to air.

State the cause of dispersion of white light passing through a glass prism. How did Newton show that white light of sun contains seven colours using two identical glass prisms. Draw a ray diagram to show the path of light when two identical glass prisms are arranged together in inverted position with respect to each other and a narrow beam of white light is allowed to fall obliquely on one of the focus of the first prism.

Give reason to justify the following: The existence of decomposers is essential in a biosphere.

Give reason to justify the following: Flow of energy in a food chain is unidirectional.

Define the following term in the context of spherical mirrors:- Pole

Define the following term in the context of spherical mirrors:- Centre of curvature

Define the following term in the context of spherical mirrors:- Principal axis

Define the following term in the context of spherical mirrors:- Principal focus

Draw ray diagrams to show the principal focus of a concave mirror.

Draw ray diagrams to show the principal focus of a convex mirror.

Consider the following diagram in which M is a mirror and P is an object and Q is its magnified image formed by the mirror.

State the type of the mirror M and one characteristic property of the image Q.

Write the function of the following part of the human eye: Cornea

Write the function of the following part of the human eye:- iris

Write the function of the following part of the human eye: crystalline lens

Write the function of the following part of the human eye: ciliary muscles

Millions of people in the developing countries of the world are suffering from corneal blindness. These persons can be cured by replacing the defective cornea with the cornea of a donated eye. A charitable society of your city has organised a campaign in your neighbourhood in order to create awareness about this fact. If you are asked to participate in this mission, how would you contribute in this noble cause?

(i) State the objective of organising such campaigns.

(ii) List two arguments which you would give to motivate the people to donate their eyes after death.

(iii) List two values which are developed in the persons who actively participate and contribute in such programmes.

(a) Draw a ray diagram to show the formation of an image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.

(b) In the above ray diagram, mark the object distance (u) and the image distance (v) with their proper signs (+ve or –ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case.

(c) Find the power of a convex lens which forms a real and inverted image of magnification –1 of an object placed at a distance of 20 cm from its optical centre.

Write the functions of the following parts in human female reproductive system:-

(i) Ovary

(ii) Oviduct

(iii) Uterus

Describe placenta structure.

Describe the function of placenta.

What is meant by speciation?

List four factors that could lead to speciation. Which of them cannot be a major factor in the speciation of a self-pollinating plant species?. Give reason to justify your answer.

Give a chemical test to distinguish between saturated and unsaturated hydrocarbons.

Name the products formed when ethane burns in the air. Write a balanced chemical equation for the reaction showing the types of energies liberated.

Why is the reaction between methane and chlorine in the presence of sunlight considered a substitution reaction?

A student obtained a sharp image of a candle flame placed at the distant end of the laboratory table on a screen using a concave mirror to determine its focal length. The teacher suggested him to focus a distant building, about 1 km away from the laboratory, for getting more correct value of the focal length. In order to focus the distant building on the same screen, the student should slightly move the

(a) mirror away from the screen

(b) screen away from the mirror

(c) screen towards the mirror

(d) screen towards the building

Select from the following the best experimental setup for tracing the path of a ray of light passing through a rectangular glass slab.

(a) P

(b) Q

(c) R

(d) S

Study the following figure in which a student has marked the angle of incidence (∠i), angle of refraction (∠r), angle of emergence (∠e), angle of prism (∠A) and the angle of deviation (∠D). The correctly marked angles are

(a) ∠A and ∠i

(b) ∠A, ∠i and ∠r

(c) ∠A, ∠i, ∠e and ∠D

(d) ∠A, ∠i, ∠r and ∠D

To determine the approximate focal length of the given convex lens by focussing a distant object (say, a sign board), you try to focus the image of the object on a screen. The image you obtain on the screen is always

(a) erect and laterally inverted

(b) erect and diminished

(c) inverted and diminished

(d) virtual, inverted and diminished

Which of the following sets of materials can be used for conducting a saponification reaction for the preparation of soap?

(a) Ca(OH)₂ and neem oil

(b) NaOH and neem oil

(c) NaOH and mineral oil

(d) Ca(OH)₂ and mineral oil

A student takes four test tubes marked P, Q, R and S of 25 mL capacity and fills 10 mL of distilled water in each. He dissolves one spoon full of four different salts in each as − KCl in P, NaCl in Q, CaCl₂ in R and MgCl₂ in S. He then adds about 2 mL of a sample of soap solution to each of the above test tubes. On shaking the contents of each of the test tubes, he is likely to observe a good amount of lather (foam) in the test tubes marked

(a) P and Q

(b) R and S

(c) P, Q and R

(d) P, Q and S

Consider the following comments about saponification reactions:

I. Heat is evolved in these reactions.

II. For quick precipitation of soap, sodium chloride is added to the reaction mixtures.

III. Saponification reactions are a special kind of neutralisation reactions.

IV. Soaps are basic salts of long-chain fatty acids.

The correct comments are

(a) I, II and III

(b) II, III and IV

(c) I, II and IV

(d) Only I and IV

Which of the following is a correct set of homologous organs?

(a) Forelimbs of frog, bird and lizard

(b) Spine of cactus and thorn of bougainvillea

(c) Wings of bat and wings of butterfly

(d) Wings of a bird and wings of a bat

A student has to perform the experiment "To identify the different parts of an embryo of a dicot seed." Select from the following an appropriate group of seeds:

(a) Pea, gram, wheat

(b) Red kidney bean, maize, gram

(c) Maize, wheat, red kidney bean

(d) Red kidney bean, pea, gram

Draw a labelled diagram to show that particular stage of binary fission in amoeba in which its nucleus elongates and divide into two and a constriction appears in its cell membrane.

A student focuses the image of a well-illuminated distant object on a screen using a convex lens. After that, he gradually moves the object towards the lens and each time focuses its image on the screen by adjusting the lens.

(i) In which direction, towards the screen or away from the screen, does he move the lens?

(ii) What happens to the size of the image? Does it decrease or increase?

(iii) What happens to the image on the screen when he moves the object very close to the lens?

What do you observe when you drop a few drops of acetic acid to test tubes containing

(a) phenolphthalein

(b) distilled water

(c) universal indicator

(d) sodium hydrogen carbonate powder