CBSE Class 10 Science 2011 Question Paper

Butanone is a four-carbon per molecule compound. Name the functional group present in it.

Why is the colour of clear sky blue ?

Why is decrease of ozone in our ozone layer a cause for our worry ?

Why are bacteria and fungi called decomposers ?

In the periodic table, how does the tendency of atoms to lose electrons change on going from (i) left to right across a period ? (ii) top to bottom in a group ?

What is meant by periodicity of properties of elements ? Why are the properties of elements placed in the same group of the periodic table similar ?

Define and show on a diagram, the following terms relating to a concave mirror : (i) Aperture (ii) Radius of curvature

Explain the formation of rainbow in the sky with the help of a diagram.

Give reasons : (i) The extent of deviation of a ray of light on passing through a glass prism depends on its colour. (ii) Lights of red colour are used for danger signals.

What is vegetative propagation ? Write two of its advantages.

Explain the terms : (i) Implantation of Zygote (ii) Placenta

Define : (i) Biomass (ii) Anaerobic degradation

What is an equitable distribution of resources in a society and why is it necessary ? State any two factors which work against an equitable distribution of resources.

(a) What is a homologous series of compounds ? List any two of its characteristics. (b) What is the next higher homologue of $C_3H_7OH$ ? What is its formula and what is it called ?

The positions of three elements A, B and C in the periodic table are indicated below : | | Group 16 | Group 17 | |---|---|---| | First Period | — | — | | Second Period | — | A | | Third Period | — | — | | Fourth Period | B | C | (a) State whether element C would be a metal or a non-metal. Why ? (b) Which is the more active element, A or C ? Why ? (c) Which type of ion (cation or anion) will be formed by the element C ? Why ?

With the help of a ray diagram explain why a convex mirror is preferred for rear view mirrors in motor cars.

What is understood by lateral displacement of light? Illustrate it with the help of a diagram. List any two factors on which the lateral displacement in a particular substance depends.

Name the three common defects of vision. What are their causes ? Name the type of lens used to correct each of them.

Expand AIDS. List any four methods of prevention (control) of AIDS.

Explain how evolutionary relationships can be traced by the study of homologous organs.

"Only variations that confer an advantage on an individual organism will survive in a population." Justify this statement.

How is the sex of the child fixed during the fertilisation step in human beings ? Explain.

Give reasons for the following : (i) Element carbon forms compounds mainly by covalent bonding. (ii) Diamond has a high melting point. (iii) Graphite is a good conductor of electricity. (iv) Acetylene burns with a sooty flame. (v) Kerosene does not decolourise Bromine water while cooking oils do. OR (a) What is a detergent ? Name one detergent. (b) Write two advantages and two disadvantages of using detergents over soaps. (c) Why, by using a detergent, can we wash clothes even in hard water ?

(a) Under what condition will a glass lens placed in a transparent liquid become invisible ? (b) Describe and illustrate with a diagram, how we should arrange two converging lenses so that a parallel beam of light entering one lens emerges as a parallel beam after passing through the second lens. (c) An object is placed at a distance of $3\text{ cm}$ from a concave lens of focal length $12\text{ cm}$. Find the (i) position and (ii) nature of the image formed. OR (a) With the help of a ray diagram explain why a concave lens diverges the rays of a parallel beam of light. (b) A $2.0\text{ cm}$ tall object is placed perpendicular to the principal axis of a concave lens of focal length $15\text{ cm}$. At what distance from the lens, should the object be placed so that it forms an image $10\text{ cm}$ from the lens ? Also find the nature and the size of image formed.

(a) Draw a diagram illustrating fertilization in a flowering plant and label on it : Male germ cell, Ovary, Female germ cell and Pollen grain. (b) Distinguish between self pollination and cross pollination. OR (a) What is spore formation ? (b) Draw a diagram showing spore formation in Rhizopus. (c) List two advantages for organisms to reproduce themselves through spores.

Dhoni obtained the image of a distant object on a screen by using a concave mirror. To find the focal length of the mirror he should measure the distance between

Which of the following can be used to find the focal length of a convex lens ?

Mohan, Sohan and Rahul separately measured the focal length of the same convex lens using the same distant tree as object. All of them measured the distance between the lens and the inverted image of the tree on the screen. Mohan obtained a sharp image on the screen and labelled the measured distance as $f_1$. Sohan obtained a slightly smaller and somewhat blurred image on the screen. He labelled the measured distance as $f_2$. Rahul obtained a slightly magnified and blurred image on the screen. He labelled the measured distance as $f_3$. The three measured values of focal length are likely to be related as

The best set-up of pins for the incident ray to trace the path of a ray of light through a rectangular glass slab is represented in the figure

While tracing the path of a ray of light through a rectangular glass slab, the four students I, II, III and IV arrived at the following different conclusions : Student I : Angle of incidence > Angle of emergence. Student II : Angle of refraction > Angle of emergence. Student III : Emergent ray is parallel to refracted ray. Student IV : Emergent ray is parallel to incident ray. The correct conclusion has been drawn by the student

On adding a clean Aluminium strip to an aqueous solution of copper sulphate, it is observed that the colour of the solution changes from ______.

An aqueous solution of zinc sulphate was taken in four test tubes. Zinc, Iron, Copper and Aluminium pieces were dropped into separate test tubes as given below : I (Zn), II (Fe), III (Cu), IV (Al). A reaction will be observed in test tubes

On shaking acetic acid with water

When solid sodium bicarbonate is added to a dilute aqueous solution of ethanoic acid

As observed in the school laboratory, acetic acid is

A slide shows a cell and another similar cell of smaller size attached to the tip of the first cell. This slide could be of

The process represented in the given diagram is

The budding in yeast is illustrated by the following diagram : I, II, III, IV

If $W_1$ is the initial mass of raisins and $W_2$ is the final mass after soaking in water, then the percentage of water absorbed by the raisins is

Instead of room temperature ($25^\circ\text{C}$), if the water used for soaking is $50^\circ\text{C}$, the percentage of water absorbed by raisins will be

The set of materials required in the experiment, "to determine the percentage of water absorbed by raisins" is