Science Delhi Set 3 2012-2013 English Medium Class 10 Question Paper Solution

Write two reasons responsible for late discovery of noble gases ?

List two measures that you would suggest for the better management of water resources.

“Cell division is a type of reproduction in unicellular organism.” Justify.

Trace the path of sperms from where they are produced in human body to the exterior. 

Write the functions of secretions of prostate gland and seminal vesicles in humans.

A ray of light falls normally on the surface of a transparent glass slab. Draw a ray diagram to show its path and also mark angle of incidence and angle of emergence.

List two advantages associated with water harvesting at the community level.

We often observe domestic waste decomposing in the bylanes of our homes. List four ways to make the residents aware that the improper disposal of wastes is harmful to the environment and also for their own health.

Complete the following chemical equations: C₂H₅OH+O₂→

Complete the following chemical equations : C₂H₅OH${\displaystyle \frac{\text{Conc.}{H}_{2}S{O}_4}{443K}}$>

Complete the following chemical equations : C₂H₅OH + Na →

Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties.

The elements Li, Na and K, each having one valence electron, are in period 2, 3 and 4 respectively of modern periodic table.

(i) In which group of the periodic table should they be ?

(ii) Which one of them is least reactive ?

(iii) Which one of them has the largest atomic radius ? Give reason in justify your answer in each case.

Given below are some elements of the modern periodic table. Atomic number of the element is given in parentheses.

A(4), B(9), C(14), D(19), E(20)

(a) Select the element that has one electron in the outermost shell. Also, write the electronic configuration of this element.

(b) Which two elements amongst these belong to the same group? Give reasons for your answer.

(c) Which two elements amongst these belong to the same period? Which one of the two has bigger atomic radius?

Write two examples of sexually transmitted diseases caused by virus.

Write two examples of sexually transmitted diseases caused by bacteri.

Explain how the transmission of virus and bacteria diseases be prevented?

Name the following : Thread like non-reproductive structures present in Rhizopus.

Name the following : 'Blobs' that develop at the tips of the non-reproductive threads in Rhizopus.

Name the following : 
Explain the structure and the function of the structures released from the ‘blobs’ in Rhizopus.

"The sex of a newborn child is a matter of chance and none of the parents may be considered responsible for it". Draw a flow chart showing determination of sex of a newborn to justify this statement.

What are fossils ?

State fossils importance in the study of evolution with the help of a suitable example. 

An object of height 4 cm is kept at a distance of 30 cm from a concave lens. Use lens formula to determine the image distance, nature and size of the image formed if focal length of the lens is 15 cm.

Mention the types of mirrors used as (i) rear view mirrors, (ii) shaving mirrors. List two reasons to justify your answers in each case.

State the difference in colours of the sun observed during sunrise/sunset and noon. Give explanation for each.

What is an ecosystem ?

List two main components of ecosystem?

We do not clean natural ponds or lakes but an aquarium needs to be cleaned regularly. Why is it so ? Explain.

Draw a sectional view of human female reproductive system and label the following parts : 

(i) Where the development of egg occurs.

(ii) Where fertilization takes place.

Describe, in brief, the changes the uterus undergoes

(i) to receive the zygote.

(ii) if zygote is not formed

(a) Identify A, B and C in the given diagram and write their functions.

(b) Mention the role of gamete and zygote in sexually reproducing organisms.

Define the term ‘isomers’.

Draw two possible isomers of the compound with molecular formula C₃H₆O and write their names.

Give the electron dot structures of the above two compounds.

A person cannot read newspaper placed nearer than 50 cm from his eyes. Name the defect of vision he is suffering from. Draw a ray diagram to illustrate this defect. List its two possible causes. Draw a ray diagram to show how this defect may be corrected using a lens of appropriate focal length.

Define the term absolute refractive index. The absolute refractive index of diamond is 2.42. What is the meaning of this statement? Refractive indices of media A, B C and D are given below:

In which of these four media is the speed of light (i) minimum and (ii) maximum ?

Find the refractive index of medium C with respect to medium B.

Select the correct statements for the process of budding in yeast:

I. A bud arises from a particular region on a parent body.

II. A parent cell divides into two daughter cells, here the parental identity is lost.

III. Before detaching from the parent body a bud may form another bud.

IV. A bud when detaches from the parent body grows into a new individual.

(A) I, II and III

(B) II, III and IV

(C) III, IV and I

(D) IV, I and II

A student after observing a slide showing different stages of binary fission in Amoeba draws the following diagrams. However these diagrams are not in proper sequence:

The correct sequence is:

(A) I, V, IV, III, II

(B) I, III, IV, V, II

(C) I, V, III, IV, II

(D) I, IV, V, III, II

In the figure, the parts marked A, B and C are sequentially:

(A) Plumule, Radicle and Cotyledon

(B) Radicle, Plumule and Cotyledon

(C) Plumule, Cotyledon and Radicle

(D) Radicle, Cotyledon and Plumule

Study the different conclusions drawn by students of a class on the basis of observations of preserved/available specimens of plants and animals.

I. Potato and sweet potato are analogous organs in plants.

II. Wings of insects and wings of birds are homologous organs in animals.

III. Wings of insects and wings of bats are analogous organs in animals.

IV. Thorns of citrus and tendrils of cucurbita are analogous organs in plants.

The correct conclusions are:

(A) I, and II

(B) II and IV

(C) I and III

(D) III and IV

You have potato, carrot, radish, sweet potato, tomato and ginger bought from the market in your jute bag. Identify two vegetables to represent the correct homologous structures.

(A) Potato and tomato

(B) Carrot and tomato

(C) Potato and sweet potato

(D) Carrot and radish

Hard water required for an experiment is not available in a school laboratory. However, following salts are available in the laboratory. Select the salts which may be dissolved in water to make it hard for the experiment.

(A) 1, 2 and 4

(B) 1, 3 and 6

(C) 3, 5 and 6

(D) 2, 4 and 5

A student prepared 20% sodium hydroxide solution in a beaker containing water. The observations noted by him are given below. 

I. Sodium hydroxide is in the form of pellets.

II. It dissolves in water readily.

III. The beaker appears cold when touched from outside.

IV. The red litmus paper turns blue when dipped into the solution.

The correct observations are:

(A) I, II, and III

(B) II, III and IV

(C) III, IV and I

(D) I, II and IV

Read the following statements: 

I. When a red litmus paper is dipped into reaction mixture of a saponification reaction, it turns blue and the reaction is exothermic.

II. When a blue litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is exothermic.

III. When a red litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is endothermic.

IV. When a blue litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is endothermic.

Which of the above statements are correct:

(A) I, and II

(B) II and III

(C) III and IV

(D) I and IV

A student takes 2 mL acetic acid in a dry test tube and adds a pinch of sodium hydrogen carbonate to it. He makes the following observations:

I. A colourless and odourless gas evolves with a brisk effervescence.

II. The gas turns lime water milky when passed through it.

III. The gas burns with an explosion when a burning splinter is brought near it.

IV. The gas extinguishes the burning splinter that is brought near it.

The correct observations are:

(A) I, II, and III

(B) II, III and IV

(C) III, IV and I

(D) IV, I and II

In an experiment to study the properties of acetic acid a student takes about 2 mL of acetic acid in a dry test tube. He adds about 2 mL of water to it and shakes the test tube well. He is likely to observe that:

(A) the acetic acid dissolves readily in water

(B) the solution becomes light orange

(C) water floats over the surface of acetic acid

(D) acetic acid floats over the surface of water

A student focussed the image of a distant object using a device ‘X’ on a white screen ‘S’ as shown in the figure. If the distance of the screen from the device is 40 cm, select the correct statement about the device.

(A) The device X is a convex lens of focal length 20 cm.

(B) The device X is a concave mirror of focal length 40 cm.

(C) The device X is a convex mirror of radius of curvature 40 cm.

(D) The device X is a convex lens of focal length 40 cm.

A student obtained a sharp image of a burning candle, placed at the farther end of a laboratory table, on a screen using a concave mirror. For getting better value of focal length of the mirror, the subject teacher suggested him for focusing a well illuminated distant object. What should the student do?

(A) He should move the mirror away from the screen.

(B) He should move the mirror slightly towards the screen.

(C) He should move the mirror as well as the screen towards the newly selected object.

(D) He should move only the screen towards the newly selected object.

Out of the five incident rays shown in the figure find the three rays that are obeying the laws of refraction and may be used for locating the position of image formed by a convex lens:

(A) 1, 2 and 3

(B) 2, 3 and 4

(C) 3, 4 and 5

(D) 1, 2 and 4

The diagrams showing the correct path of the ray after passing through the lens are:

I	II
III	IV

II and III only

I and II only

I, II and III

I, II and IV

While performing the experiment to trace the path of a ray of light passing through a glass prism, four students marked the incident ray and the emergent ray in their diagrams in the manner shown below. 

(A) I

(B) II

(C) III

(D) IV

In an experiment to trace the path of a ray of light through a glass prism for different values of angle of incidence a student would find that the emergent ray: 

(A) is parallel to the incident ray

(B) perpendicular to the incident ray

(C) is parallel to the refracted ray

(D) bends at an angle to the direction of incident ray

After tracing the path of rays of light through a glass slab for three different angles of incidence, a student measured the corresponding values angle of refraction r and angle of emergence e and recorded them in the table given below: 

The correct observations are:

(A) I and II

(B) II and III

(C) I and III

(D) I, II and III

Select from the following the best set-up for tracing the path of a ray of light through a rectangular glass slab: 

(A) I

(B) II

(C) III

(D) IV