Science Foreign Set 1 2015-2016 English Medium Class 10 Question Paper Solution

Which element exhibits the property of catenation to maximum extent and why?

Name the method by which hydra reproduces. Is this method sexual or asexual?

We often use the word environment. What does it mean?

AB and CD, two spherical mirrors, from parts of a hollow spherical ball with its centre at O as shown in the diagram. If arc AB = `1/2` arc CD, what is the ratio of their focal lengths? State which of the two mirrors will always form virtual image of an object placed in front of it and why.

What is sustainable development? State its two main objectives.

List four causes of damage to forests.

Write the name and molecular formula of an organic compound having its name suffixed with 'ol' and having two carbon atoms in its molecule. Write balanced chemical equation to indicate what happens when this compound is heated with excess conc. H₂SO₄ and the name of main product formed. Also state the role of conc. H₂SO₄ in the reaction.

An organic compound 'P' is a constituent of wine. 'P' on reacting with acidified K₂Cr₂O₇ forms another compound 'Q'. When a piece of sodium is added to 'Q' a gas 'R' evolves which burns with a pop sound. Identify P, Q and R and write the chemical equations of the reactions involved.

State the main aim of classifying elements. Which is the more fundamental property of elements that is used in the development of Modern Periodic Table? Name and state the law based on this fundamental property. On which side of the periodic table one can find metals, non-metals and metalloids?

An element 'X' (Atomic number – 20) burns in the presence of oxygen to form a basic oxide.
(a) Identify the element and write its electronic configuration.
(b) State its group number and period number in the Modern Periodic Table.
(c) Write a balanced chemical equation for the reaction when this oxide is dissolved in water.

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

Answer the following question.

What is pollination? Explain the different types of pollination.

What happens when a Planaria gets cut into two pieces?

What happens when a mature spirogyra filament attains considerable length?

What happens when on maturation sporangia burst?

What is sexual reproduction? List its four significances.

List two differences in tabular form between dominant trait and recessive traits. What percentage/proportion of the plants in the F₂ generation/progeny were round, in Mendel's cross between round and wrinkled pea plants?

List three factors that provide evidences in favour of evolution in organisms and state the role of each in brief.

If the image formed by a lens for all positions of the object placed in front of it is always virtual, erect and diminished, state the type of the lens. Draw a ray diagram in support of your answer. If the numerical value of focal length of such a lens is 20 cm, find its power in new cartesian sign conventions.

Explain in brief the reason for the following :
Advanced sunrise

Explain in brief the reason for the following :
Delayed sunset

Explain in brief the reason for the following:

Twinkling of stars

While discussing about coal and petroleum a teacher told his students about PCRA's (Petroleum Conservation Research Association) guidelines to save the fossil fuels while driving vehicles. Deepa was going to her school with her mother who was driving car. At the traffic signal, when the light was red, Deepa suggested her mother to switch of the engine.
After reading the above passage, answer the following questions :
(a) Fossil fuels are natural resources, then why do we need to conserve them?
(b) List any two ways of saving the fossil fuels.
(c) State two values exhibited to Deepa.

You have three unlabelled test tubes containing ethanol, ethanoic acid and soap solution. Explain the method you would use to identify the compounds in different test tubes by chemical tests using litmus paper and sodium metal.

Give the reason of formation of scum when soaps are used with hard water.

What is vegetative propagation? List with brief explanation three advantages of practising this process for growing some types of plants. Select two plants from the following which are grown by this process:
Banana, Wheat, Mustard, Jasmine, Gram.

Why did Mendel choose garden pea for his experiments? Write two reasons.

List two contrasting visible characters of garden pea Mendel used for his experiment.

Explain in brief how Mendel interpreted his results to show that the traits may be dominant or recessive.

Suppose you have three concave mirrors A, B and C of focal lengths 10 cm, 15 cm and 20 cm. For each concave mirror you perform the experiment of image formation for three values of object distance of 10 cm, 20 cm and 30 cm. Giving reason answer the following:

(a) For the three object distances, identify the mirror/mirrors which will form an image of magnification – 1.
(b) Out of the three mirrors identify the mirror which would be preferred to be used for shaving purposes/makeup.
(c) For the mirror B draw ray diagram for image formation for object distances 10 cm and 20 cm.

At what distance from a concave lens of focal length 20 cm a 6 cm tall object be placed so as to obtain its image at 15 cm from the lens? Also calculate the size of the image formed.
Draw a ray diagram to justify your answer  for the above situation and label it.

Define the term dispersion of white light.

State the cause of dispersion of white light

Consider the following oils :

(I) Mobil oil

(II) Castor oil

(III) Turpentine oil

(IV) Kerosene

(V) Mustard oil

(VI) Coconut oil

Which of these can be used for prepartion of soap?

(a) I, II, III, VI

(b) II, V, VI

(c) II, III, V, VI

(d) II, III, VI

The chemical mostly used in the preparation of most of the soaps we use is

(a) Sodium chloride

(b) Potassium hydroxide

(c) Sodium hydroxide

(a) Potassium chloride

A student is testing water to know which is best for cleansing purposes with soaps. He would find that the cleansing action of soaps is best when he uses water obtained from

(a) rain

(b) tap

(c) hand pump

(d) pond

A student determines the focal length of a device 'X' by focusing the image of a distant object on a screen placed 20 cm from the device on the same side as the object. The device 'X' is

(a) Concave lens of focal length 10 cm

(b) Convex lens of focal length 20 cm

(c) Concave mirror of focal length 10 cm

(d) Concave mirror of focal length 20 cm

A teacher sets up the stand carrying a convex lens of focal length 15 cm at 42.7 cm mark on the optical bench. He asks four students A, B, C and D to suggest the position of screen on the optical bench so that a distinct image of a distant tree is obtained almost immediately on it. The positions suggested by the students were as

A. 12.7 cm

B. 29.7 cm

C. 57.7 cm

D. 72.7 cm

The correct position of the screen was suggested by

(a) A

(b) B

(c) C

(d) D

A student has traced the path of a ray of light through a glass slab as follows. If you are asked to label 1, 2, 3 and 4, the correct sequencing of labeling  ∠i, ∠e, ∠r and lateral displacement respectively is

(a) 2, 1, 3, 4

(b) 1, 2, 3, 4

(c) 1, 3, 2, 4

(d) 1, 3, 4, 2

In an experiment to trace the path of a ray of light through a triangular glass prism, a student would observe that the emergent ray

(a) is parallel to the incident ray.

(b) is along the same direction of incident ray.

(c) gets deviated and bends towards the thinner part of the prism.

(d) gets deviated and bends towards the thicker part (base) of the prism.

The students of a class were asked by the teacher to study the different parts of an embryo of an angiosperm. Given below are the essential steps for the experiment :

A. Soak the seeds in plain water and keep them overnight.

B. Cut open the soaked seed and observe its different parts.

C. Take some healthy seeds in a petri-dish.

D. Drain the excess water, cover the seeds with a wet cotton cloth and leave them as it is for a day.

The correct sequence of these steps is

(a) C, A, D, B

(b) C, D, A, B

(c) A, C, D, B

(d) A, C, B, D

The following vegetables are kept in a basket :

Potato, Tomato, Radish, Brinjal, Carrot, Bottle-gourd

Which two of these vegetables correctly represent the homologous structures?

(A) Carrot and Tomato

(B) Potato and Brinjal

(C) Radish and Carrot

(D) Radish and Bottle-gourd

A student is studying the properties of acetic acid in his school laboratory. List two physical and two chemical properties which he must observe and note in his record book.

Name the type of asexual reproduction in which two individuals are formed from a single parent and the parental identity is lost. Draw the initial and the final stages of this type of reproduction. State the event with which this reproduction starts.

To find the image distance for varying object distances in case of a convex lens of focal length 15 cm, a student obtains on a screen a sharp image of a bright object by placing it at 20 cm distance from the lens. After that he gradually moves the object away from the lens and each time focuses the image on the screen.

(a) In which direction-towards or away from the lens does he move the screen to focus the object?

(b) How does the size of image change?

(c) Approximately at what distance does he obtain the image of magnification –1?

(d) How does the intensity of image change as the object moves farther and farther away from the lens?