Science 31/1/3 2018-2019 English Medium Class 10 Question Paper Solution

If you could use any source of energy for heating your food which one would you prefer? State one reason for your choice. 

Write the function of the voltmeter in an electric circuit.

What happens to the image distance in the normal human eye when we decrease the distance of an object, say 10 m to 1 m? Justify your answer. 

List two different functions performed by the pancreas in our body.

Answer the following question.
How it can be proved that the basic structure of the Modern Periodic Table is based on the electronic configuration of atoms of different elements?

The electronic configuration of an element is 2, 8, 4. State it: 
group and period in the Modern Periodic Table.

The electronic configuration of an element is 2, 8, 4. State it: 
name and write its one physical property.

Answer the following question.
How can we help in reducing the problem of waste disposal? Suggest any three methods.

Answer the following question.
Define an ecosystem. Draw a block diagram to show the flow of energy in an ecosystem.

List three advantages of:

Exploiting resources with short term aims.

List three advantages of: 

Using a long term perspective in managing our natural resources. 

What is a rainbow? Draw a labelled diagram to show the formation of a rainbow.

Nervous and hormonal systems together perform the function of control and coordination in human beings. Justify this statement with the help of an example.

Answer the following question.
Trace the sequence of events Whichoccur when a bright light is focused on your eyes.

What is photosynthesis?

Answer the following question.
Name the plant Mendel used for his experiment. What type of progeny was obtained by Mendel in F₁ and F₂ generations when he crossed the tall and short plants? Write the ratio he obtained in F₂ generation plants.

List three distinguishing features, in tabular form, between acquired traits and the inherited traits.

Answer the following question.
2 g of silver chloride is taken in a china dish and the china dish is placed in sunlight for some time. What will be your observation in this case? Write the chemical reaction involved in the form of a balanced chemical equation. Identify the type of chemical reaction.

Identify the type of reaction taking place of the following case and write the balanced chemical equation of the reaction:
Zinc reacts with silver nitrate to produce zinc nitrate and silver.

Identify the type of reaction taking place of the following case and write the balanced chemical equation of the reaction:
Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.

Based on the group valency of element write the molecular formula of the following compound giving justification:
Oxide of first group elements.

Based on the group valency of element write the molecular formula of the following compound giving justification:

Halide of the elements of group thirteen

Based on the group valency of element write the molecular formula of the following compound giving justification:

Compound formed when an element A of group 2 combines with an element B of group seventeen.

Explain the following: 

Sodium chloride is an ionic compound which does not conduct electricity in solid state whereas it does conduct electricity in the molten state as well as in an aqueous solution.

Explain the following: 

Reactivity of aluminium decrease if it is dipped in nitric acid.

Explain the following:

Metals like calcium and magnesium are never found in their free state in nature.

Answer the following question.
With the help of a suitable circuit diagram prove that the reciprocal of the equivalent resistance of a group of resistances joined in parallel is equal to the sum of the reciprocals of the individual resistances. 

Solve the following question:
In an electric circuit, two resistors of 12 0 each are joined in parallel to a 6 V battery. Find the current drawn from the battery.

Answer the following question.
An electric lamp of resistance 20 Ω and a conductor of resistance 4 0 are connected to a 6 V battery as shown in the circuit. Calculate: 

(a) the total resistance of the circuit,  

(b) the current through the circuit, 

(c) the potential difference across the  (i) electric lamp and (ii) conductor, and

(d) power of the lamp.

Draw magnetic field lines produced around a current-carrying straight conductor passing through cardboard. Name, state and apply the rule to mark the direction of these field lines.

Draw magnetic field lines produced around a straight current carrying conductor passing through a cardboard. How will the strength of the magnetic field change when the point where magnetic field is to be determined is moved away from the conductor?

An object is placed at a distance of 60 cm from a concave lens of focal length 30 cm.
(i) Use the lens formula to find the distance of the image from the lens.
(ii) List four characteristics of the image (nature, position, size, erect/inverted) formed by the lens in this case.
(iii) Draw a ray diagram to justify your answer of the part (ii).

Answer the following question.
How does suitable pollination lead to fertilization?

Identify the given diagram.
Name the parts 1 to 5. 

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What is contraception? List three advantages of adopting contraceptive measures.

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Write the chemical formula and name of the compound which is the active ingredient of all alcoholic drinks. List its two uses.

Write the chemical equation and name of the product formed when this compound reacts with -
(i) Sodium metal  
(ii) hot concentrated sulphuric acid

Answer the following question.
What is methane? Draw its electron dot structure. Name the type of bonds formed in this compound. Why are such compounds:
(i) poor conductors of electricity? and  
(ii) have low melting and boiling points? What happens when this compound burns in oxygen?

Write the main difference between an acid and a base. 

With the help of suitable examples explain the term neutralization and the formation of –

1. acidic,
2. basic and
3. neutral salts

Answer the following question.
In the experimental set up to show that "CO2 is given out during respiration", name the substance taken in the small test tube kept in the conical flask. State its function and the consequence of its use.

A student is observing the temporary mount of a leaf peel under a microscope. Draw a labelled diagram of the structure of stomata as seen under the microscope

Draw labelled diagrams to illustrate budding in Hydra.

Answer the following question.
List four precautions which a student should observe while determining the focal length of a given convex lens by obtaining an image of a distant object on a screen. 

Answer the following question.
While studying the dependence of potential difference ( V) across a resistor on the current (I) passing through it, in order to determine the resistance of the resistor, a student took 5 readings for different values of current and plotted a graph between V and t. He got a straight line graph passing through the origin. What does the straight-line signify? Write the method of determining the resistance of the resister using this graph. 

What would you suggest to a student if while performing an experiment he finds that the pointer/needle of the ammeter and voltmeter do not coincide with the zero marks on the scales when the circuit is open? No extra ammeter/voltmeter is available in the laboratory.

Answer the following question.
In three test tubes A, B, and C, three different liquids namely, distilled water, underground water and distilled water in which a pinch of calcium sulphate is dissolved, respectively are taken. Equal amount of soap Answer is added to each test tube and the contents are shaken. In which test tube will the length of the foam (lather) be longest? Justify your answer.

Blue litmus is added to two test tubes A and B containing dilute HCl and NaOH. Answer respectively. In which test tube a colour change will be observed? State the colour change and give its reason.

Answer the following question.
What is observed when 2 mL of dilute hydrochloric acid is added to 1 g of sodium carbonate taken in a clean and dry test tube? Write a chemical equation for the reaction involved.