Science Class X

Reflection & Refraction (C10)

The absolute refractive index of Ruby is 1.7. Find the speed of light in Ruby. The speed of light in vacuum is 3 × 108 m/s.

Chemical Reactions & Equations (C10)

On heating blue coloured powder of copper (II) nitrate in a boiling tube, black copper oxide, O2 and a brown gas X is formed.

  1. Identify the type of reaction and the gas X.
  2. Write balanced chemical equation of the reaction.
  3. Write the pH range of aqueous solution of the gas X.

Acids, Bases & Salts (C10)

(a) While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid ?

(b) Dry hydrogen chloride gas does not change the colour of dry litmus paper. Why ?

Acids, Bases & Salts (C10)

How is sodium hydroxide manufactured in industries ? Name the process. In this process a gas X is formed as by-product. This gas reacts with lime water to give a compound Y, which is used as a bleaching agent in the chemical industry. Identify X and Y and write the chemical equation of the reactions involved.

Acids, Bases & Salts (C10)

What are amphoteric oxides ? Give an example. Write balanced chemical equations to justify your answer.

Carbon & its Compounds (C10)

What is a homologous series of carbon compounds ? Give an example and list its three characteristics.

Life Processes (C10)

List in tabular form three distinguishing features between autotrophic nutrition and heterotrophic nutrition.

Life Processes (C10)

(a) What is translocation ? Why is it essential for plants ?

(b) Where do the substances in plants reach as a result of translocation ?

Reflection & Refraction (C10)

A 10 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 12 cm. The distance of the object from the lens is 18 cm. Find the nature, position and size of the image formed.

Our Environment (C10)

Write the essential function performed by ozone at the higher levels of the Earth’s atmosphere ? How is it produced ? Name the synthetic chemicals mainly responsible for the drop of amount of ozone in the atmosphere. How can the use of these chemicals be reduced ?

Sources of Energy (C10)

What are solar cells ? Explain the structure of solar panel. List two principal advantages associated with solar cells.

Periodic Classification of Elements (C10)

The electrons in the atoms of four elements A, B, C and D are distributed in three shells having 1, 3, 5 and 7 electrons respectively in their outermost shells. Write the group numbers in which these elements are placed in the Modern Periodic Table. Write the electronic configuration of the atoms of B and D and the molecular formula of the compound formed when B and D combine.

Periodic Classification of Elements (C10)

How does the metallic character of elements vary on moving from

  1. left to right in a period,
  2. from top to bottom in a group

of the Modern Periodic Table ? Give reason for your answer.

Control & Coordination (C10)

Why is the use of iodised salt advisable ? Name the disease caused due to deficiency of iodine in our diet and state its one symptom.

Life Processes (C10)

What is hydrotropism ? Design an experiment to demonstrate this phenomenon.

Life Processes (C10)

What are homologous structures ? Give an example.

Electricity (C10)

Consider the given circuit and find the current flowing in the circuit and potential difference across the 15 Ω resistor when the circuit is closed.

Science Practical (C10)

A teacher provided acetic acid, water, lemon juice, aqueous solution of sodium hydrogen carbonate and sodium hydroxide to students in the school laboratory to determine the pH values of these substances using pH papers. One of the students reported the pH values of the given substances as 3, 12, 4, 8 and 14 respectively. Which one of these values is not correct ? Write its correct value stating the reason.

Science Practical (C10)

What would a student report nearly after 30 minutes of placing duly cleaned strips of aluminium, copper, iron and zinc in freshly prepared iron sulphate solution taken in four beakers ?

Science Practical (C10)

What is observed when a pinch of sodium hydrogen carbonate is added to 2 mL of acetic acid taken in a test tube ? Write chemical equation for the reaction involved in this case.

Science Practical (C10)

After examining a prepared slide under the high power of a compound microscope, a student concludes that the given slide shows the various stages of binary fission in a unicellular organism. Write two observations on the basis of which such a conclusion may be drawn.

Science Practical (C10)

List in proper sequence four steps of obtaining germinating dicot seeds.

Science Practical (C10)

List four precautions which a student should observe while preparing a temporary mount of a leaf peel to show stomata in his school laboratory.

Science Practical (C10)

The current flowing through a resistor connected in a circuit and the potential difference developed across its ends are as shown in the diagram by milliammeter and voltmeter readings respectively:

  1. What are the least counts of these meters ?
  2. What is the resistance of the resistor ?

Carbon & its Compounds (C10)

Carbon has four electrons in its valence shell. Which type of compounds can be formed by carbon atom and why ? Give any one example of such compounds.

Reflection & Refraction (C10)

An object is kept 40 cm in front of a concave mirror of focal length 20 cm. Find the position and nature of the image. Draw a ray diagram to show the formation of image in this case.

Chemical Reactions & Equations (C10)

In the reaction:

MnO2 + 4HCl → MnCl2 + 2H2O + Cl2

  1. Name the compound (i) oxidised, (ii) reduced.
  2. Define oxidation and reduction on its basis.

Acids, Bases & Salts (C10)

(a) For the preparation of cakes, baking powder is used. If at home your mother uses baking soda instead of baking powder, how will it affect the taste of the cake and why?

(b) How is baking soda be converted into baking powder?

(c) What makes the cake soft and spongy?

Acids, Bases & Salts (C10)

In the electrolysis of water,

  1. Name the gas collected at anode and cathode?
  2. Why is the volume of gas collected at one electrode double than the other?
  3. What would happen if dil H2SO4 is not added to water?

Acids, Bases & Salts (C10)

"pH has a great importance in our daily life". Explain by giving three examples.

Acids, Bases & Salts (C10)

A compound which is prepared from gypsum has the property of hardening when mixed with a proper quantity of water. Identify the compound and write its chemical formula. Write the chemical equation for its preparation. Mention any one use of the compound.

Acids, Bases & Salts (C10)

1 g of solid sodium chloride is taken in a clean and dry test tube and 2 mL of conc. sulphuric acid is added to it. If the gas evolved is tested first with dry and then with wet blue litmus paper, in which case will the litmus paper change colour? Give reason for your answer. What inference can be drawn about the nature of the evolved gas ? Support your answer with chemical equation for the reaction.

Carbon & its Compounds (C10)

Draw the structural formulae of all the possible isomers of the compound with the molecular formula C3H6O and also give their electron dot structures.

Carbon & its Compounds (C10)

What happens when hydrogen is added to a vegetable oil in the presence of nickel? Name the reaction and write one difference between the physical property of the vegetable oil and the product obtained in this reaction. Write the role of nickel in this reaction.

Reflection & Refraction (C10)

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?

Reflection & Refraction (C10)

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?

Heredity & Evolution (C10)

How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism?

Heredity & Evolution (C10)

With the help of one example for each, distinguish between the acquired traits and the inherited traits. Why are the traits / experiences acquired during the entire lifetime of an individual not inherited in the next generation? Explain the reason of this fact with an example.

Heredity & Evolution (C10)

What are acquired traits? Why are these traits generally not inherited over generations? Explain.

Reflection & Refraction (C10)

We wish to obtain an equal sized inverted image of a candle flame on a screen kept at distance of 4 m from the candle flame.

  1. Name the type of lens that should be used.
  2. What should be the focal length of the lens and at what distance from the candle flame the lens be placed.
  3. Draw a labelled diagram to show the image formation in this case.

Reflection & Refraction (C10)

A 5 cm tall object is placed at a distance of 30 cm from a convex mirror of focal length 15 cm. Find the position, size and nature of the image formed.

Electricity (C10)

What is electrical resistivity? Derive its SI unit. In a series electrical circuit comprising a resistor made up of a metallic wire, the ammeter reads 100 mA. If the length of the wire is doubled, how will the current in the circuit change? Justify your answer.

Electricity (C10)

Consider the following circuit:

 

What would be the readings of the ammeter and the voltmeter when key is closed? Give reason to justify your answers.

Electricity (C10)

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.

Electricity (C10)

Calculate the total cost of running the following electrical devices in the month of September, if the rate of 1 unit of electricity is Rs 6.00.

  1. Electric heater of 1000 W for 5 hours daily.
  2. Electric refrigerator of 400 W for 10 hours daily.