# Science Class X

What is a dam? Why do we seek to build large dams? While building large dams, which three main problems should particularly be addressed to maintain peace among local people ? Mention them.

Students in a school listened to the news read in the morning assembly that the mountain of garbage in Delhi, suddenly exploded and various vehicles got buried under it. Several people were also injured and there was traffic jam all around. In the brain storming session the teacher also discussed this issue and asked the students to find out a solution to the problem of garbage. Finally they arrived at two main points - one is self management of the garbage we produce and the second is to generate less garbage at individual level.

(a) Suggest two measures to manage the garbage we produce.

(b) As an individual, what can we do to generate the least garbage ? Give two points.

(c) List two values the teacher instilled in his students in this episode.

If the image formed by a spherical mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it? Draw a labelled ray diagram to support your answer.

A compound ‘X’ on heating with excess conc. sulphuric acid at 443 K gives an unsaturated compound ‘Y’. ‘X’ also reacts with sodium metal to evolve a colourless gas ‘Z’. Identify ‘X’, ‘Y’ and ‘Z’. Write the equation of the chemical reaction of formation of ‘Y’ and also write the role of sulphuric acid in the reaction.

Write a and b in the given flow chart of neuron through which information travels as an electrical impulse.

Write Joule’s law of heating.

What is meant by power of a lens? Write its SI unit. A student uses a lens of focal length 40 cm and another of –20 cm. Write the nature and power of each lens.

State the laws of refraction of light. Explain the term 'absolute refractive index of a medium' and write an expression to relate it with the speed of light in vacuum.

Name the hormones secreted by the following endocrine glands and specify one function of each:

(a) Thyroid (b) Pituitary (c) Pancreas

Write one main difference between asexual and sexual mode of reproduction. Which species is likely to have comparatively better chances of survival - the one reproducing asexually or the one reproducing sexually? Give reason to justify your answer.

Why are alloys commonly used in electrical heating devices? Give reason.

Why are metals good conductors of electricity whereas glass is a bad conductor of electricity? Give reason.

List the factors on which the resistance of a conductor in the shape of a wire depends.

Why are most carbon compounds poor conductors of electricity?

2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a test tube. When the contents are warmed, a gas evolves which is bubbled through a soap solution before testing. Write the equation of the chemical reaction involved and the test to detect the gas. Name the gas which will be evolved when the same metal reacts with dilute solution of a strong acid.

Decomposition reactions require energy either in the form of heat or light or electricity for breaking down the reactants. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light and electricity.

(a) Mention any two components of blood.

(b) Trace the movement of oxygenated blood in the body.

(c) Write the function of valves present in between atria and ventricles.

(d) Write one structural difference between the composition of artery and veins.

(a) Define excretion.

(b) Name the basic filtration unit present in the kidney.

(c) Draw excretory system in human beings and label the following organs of excretory system which perform following functions:
(i) form urine
(ii) is a long tube which collects urine from kidney
(iii) store urine until it is passed out

Describe in brief the structure and function of placenta?

Write the function of following parts in human female reproductive system:

1. Ovary
2. Oviduct
3. Uterus

How is copper extracted from its sulphide ore? Explain the various steps supported by chemical equations. Draw labelled diagram for the electrolytic refining of copper.

Write the steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores.

(a) The modern periodic table has been evolved through the early attempts of Dobereiner, Newland and Mendeleev. List one advantage and one limitation of all the three attempts.

(b) Name the scientist who first of all showed that atomic number of an element is a more fundamental property than its atomic mass.

(c) State Modern periodic law.

Why does the sun appear reddish early in the morning? Will this phenomenon be observed by an astronaut on the Moon? Give reason to justify your answer.

Write the function of each of the following parts of human eye:

1. Cornea
2. Iris
3. Crystalline lens
4. Ciliary muscles

Why do stars twinkle? Explain.

A student is unable to see clearly the words written on the black board placed at a distance of approximately 3 m from him. Name the defect of vision the boy is suffering from. State the possible causes of this defect and explain the method of correcting it.

Write the principle of working of an electric motor. Explain the function of the following parts of an electric motor:

1. Armature
2. Brushes
3. Split ring

State Fleming’s left hand rule.

Name the process by which an amoeba reproduces. Draw the various stages of its reproduction in a proper sequence.

What is observed when a solution of sodium sulphate is added to a solution of barium chloride taken in a test tube? Write equation for the chemical reaction involved and name the type of reaction in this case.

A student added few pieces of aluminium metal to two test tubes A and B containing aqueous solutions of iron sulphate and copper sulphate. In the second part of her experiment, she added iron metal to another test tubes C and D containing aqueous solutions of aluminium sulphate and copper sulphate.

In which test tube or test tubes will she observe colour change? On the basis of this experiment, state which one is the most reactive metal and why.

An object of height 4.0 cm is placed at a distance of 30 cm from the optical centre ‘O’ of a convex lens of focal length 20 cm. Draw a ray diagram to find the position and size of the image formed. Mark optical centre ‘O’ and principal focus ‘F’ on the diagram. Also find the approximate ratio of size of the image to the size of the object.

List the steps of preparation of temporary mount of a leaf peel to observe stomata?

"Improvements in our lifestyle have resulted in greater amounts of waste generation." Give two examples to support the given statement. Suggest one change that we can incorporate in our lifestyle in order to reduce non biodegradable waste.

The following organisms form a food chain.
Insect, Hawk, Grass, Snake, Frog

Which of these will have highest concentration of non-biodegradable chemicals? Name the phenomenon.

Why is there a need to harness non-conventional sources of energy? Give two main reasons.

"Human beings occupy the top level in any food chain." What are the consequences of this on our body?

What do you understand by "Watershed Management"? List any two advantages of watershed management.

With the help of a labelled circuit diagram wire describe an activity to illustrate the pattern of the magnetic field lines around a straight current carrying long conducting wire.

i) Name the rule that is used to find the direction of magnetic field associated with a current carrying conductor.

ii) Is there a similar magnetic field produced around a thin beam of moving (a) alpha particles and (b) neutrons? Justify your answer.

Draw a circuit diagram of an electric circuit containing a cell, a key, an ammeter, a resistor of 4Ω in series with a combination of two resistors (8Ω each) in parallel and a voltmeter across parallel combination. Each of them dissipate maximum energy and can withstand a maximum power of 16W without melting. Find the maximum current that can flow through the three resistors.

Name the electric device that converts mechanical energy into electrical energy. Draw the labelled diagram and explain the principle involved in this device.

State the cause of dispersion of white light by a glass prism. How did Newton, using two identical glass prisms, show that white light is made of seven colours? Draw a ray diagram to show the path of a narrow beam of white light, through a combination of two identical prisms arranged together in inverted position with respect to each other, when it is allowed to fall obliquely on one of the faces of the first prism of the combination.

Draw a path of light ray passing through a prism. Label angle of incidence and angle of deviation in the ray diagram.

Noopur needs a lens of power -4.5D for correction of her vision.

a) What kind of defect in vision is she suffering from?
b) What is the focal length and nature of the corrective lens?
c) Draw ray diagrams showing the (a) defected eye and (b) correction for this defect.
d) What are the causes of this defect?

Rohit focused the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle, screen and lens as under:
Position of candle = 26.0 cm
Position of convex lens = 50.0 cm
Position of screen = 74.0 cm
i) What is the focal length of the convex lens?
ii) Where will the image be formed if he shifts the candle towards the lens at a position of 38 cm?
iii) Draw a ray diagram to show the formation of the image in case (ii) as said above?

An object of height 1.2 m is placed before a concave mirror of focal length 20 cm so that a real image is formed at a distance of 60 cm from it. Find the position of an object. What will be the height of the image formed?

Mention any one point of difference between Pepsin and Trypsin.

Give an example of a flower which contains both stamens and carpels.

List three differences between arteries and veins.