Now find out:
[question] Question. Now find out: (i) Why are Tiruvanantapuram and Shillong rainier in June than in July? (ii) Why is July rainier in Mumbai than in Tiruvanantapuram? (iii) Why are south-west monsoons less rainy in Chennai? (iv) Why is Shillong rainier than Kolkata? (v) Why is Kolkata rainier in July than in June unlike Shillong which is rainier in June than in July? (vi) Why does Delhi receive more rain than Jodhpur? [/question] [solution] Solution: (i) The south-west monsoons hit Tiruvanantap...
Read More →ANSWER The following
[question] Question. (i) Name two rainiest stations. (ii) Name two driest stations. (iii) Two stations with most equable climate. (iv) Two stations with most extreme climate. (v) Two stations most influenced by the Arabian branch of southwest monsoons. (vi) Two stations most influenced by the Bay of Bengal branch of south-west monsoons. (vii) Two stations influenced by both branches of the south-west monsoons (viii) Two stations influenced by retreating and north-east monsoons. (ix) Two stations...
Read More →. A person has a hearing range from 20 Hz to 20 kHz
[question] Question. A person has a hearing range from $20 \mathrm{~Hz}$ to $20 \mathrm{kHz}$. What are the typical wavelengths of sound waves in air corresponding to these two frequencies? Take the speed of sound in air as $344 \mathrm{~ms}^{-1}$. [question] [solution] Solution: Given, speed of sound, $\mathrm{v}=344 \mathrm{~ms}^{-1}$ For frequency $v_{1}=20 \mathrm{~Hz}$, wavelength, $\lambda_{1}=?$ Wavelength of sound of frequency $20 \mathrm{~Hz}$ $\lambda_{1}=\frac{v}{v_{1}}=\frac{344}{20}...
Read More →What are the environmental consequences of the increasing demand for energy ?
[question] Question. What are the environmental consequences of the increasing demand for energy ? What steps would you suggest to reduce energy consumption ? [/question] [solution] solution: (i) Burning of fossil fuels to meet increasing demand for energy causes air-pollution. (ii) Construction of dams on rivers to generate hydro-electricity destroys large ecosystems which get submerged under water in the dams. Large amounts of methane (which is a greenhouse gas) is produced when submerged vege...
Read More →Find the odd one out and say why.
[question] Question. Find the odd one out and say why. (i) Tourist guide, dhobi, tailor, potter (ii) Teacher, doctor, vegetable vendor, lawyer (iii) Postman, cobbler, soldier, police constable (iv) MTNL, Indian Railways, Air India, SAHARA Airlines, All India Radio [/question] [solution] Solution: (i) Tourist guide He is appointed by the government, while dhobi, tailor and potter belong to the private sector. (ii) Vegetable vendor His is the only profession that does not require a formal educatio...
Read More →What are the advantages and disadvantages of using a solar cooker ?
[question] Question. What are the advantages and disadvantages of using a solar cooker ? Are there places where solar cookers would have limited utility ? [/question] [solution] solution: Advantages of solar cooker (1) Using solar cooker saves our conventional fuels. (2) Solar cookers do not cause any environmental pollution. (3) The nutrients in the food are not destred if the food is prepared in solar cooker as the temperature inside it is not so high. (4) Four food items can be cooked at a ti...
Read More →Flash and thunder are produced simultaneously.
[question] Question. Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen. Why ? [/question] [solution] Solution: The speed of light is $3 \times 10^{8} \mathrm{~ms}^{-1}$ and the speed of sound is $344 \mathrm{~ms}^{-1}$ in air. That is, the speed of light is very large as compared to the speed of sound. Thus, flash of lightning is seen at first, but sound takes a little bit more time to reach our ears. [/solution]...
Read More →Match the following:
[question] Question. Match the following: [/question] [solution] Solution: [/solution]...
Read More →Re-arrange the ten stations in two different sequences:
[question] Question. Re-arrange the ten stations in two different sequences: (i) According to their distance from the equator. (ii) According to their altitude above mean sea-level. [/question] [solution] Solution: (i) According to their distance from the equator: Tiruvanantapuram (closest) Bangalore Chennai Mumbai Nagpur Kolkata Shillong Jodhpur Delhi Leh (farthest) (ii) According to their altitude above mean sea-level: Kolkata (lowest) Chennai Mumbai Tiruvanatapuram Delhi Jodhpur Nagpur Bangal...
Read More →Which characteristic of the sound helps you to identify
[question] Question. Which characteristic of the sound helps you to identify your friend by his voice while sittingwith others in a dark room ? [/question] [solution] Solution: The characteristic of sound that helps you to identify your friend's voice is 'quality' or 'timbre'. [/solution]...
Read More →Why is sound wave called a longitudinal wave ?
[question] Question. Why is sound wave called a longitudinal wave ? [/question] [solution] Solution: Sound wave is called longitudinal wave because the particles of the medium vibrate in the direction of the propagation of wave. [/solution]...
Read More →Choose the most appropriate answer.
[question] Question. Choose the most appropriate answer. (a) The sectors are classified into public and private sector on the basis of: (i) employment conditions (ii) the nature of economic activity (iii) ownership of enterprises (iv) number of workers employed in the enterprise (b) Production of a commodity, mostly through the natural process, is an activity in ______________ sector. (i) primary (ii) secondary (iii) tertiary (iv) information technology (c) GDP is the total value of ____________...
Read More →What are the qualities of an ideal source of energy?
[question] Question. What are the qualities of an ideal source of energy? [/question] [solution] solution: (1) It should have a high calorific value [calorific value is defined as the number of heat units produced when unit mass of fuel is burnt] Thus, a good fuel should liberate more heat per unit mass. (2) It should have low moisture content. (3) It should have low non-combustible matter like ash, etc. That is, it should leave low ash and other residual matter after combustion. (4) Its product...
Read More →Give an experiment to show that sound needs a material medium for its propagation.
[question] Question. Give an experiment to show that sound needs a material medium for its propagation. [/question] [solution] Solution: Take an electric circuit which consists of a power supply source, a switch and an electric bell arranged inside a bell jar, which stands on the platform of a vacuum pump. The switch of the bell is pressed to close the electric circuit. When there is air within the bell jar, sound is heard. Air is now pumped out of the bell jar. When the air is completely remove...
Read More →On what basis would you classify
[question] Question. On what basis would you classify energy sources as (a) renewable and non-renewable ? (b) exhaustible and inexhaustible ? Are the options given in (a) and (b) the same ? [solution] solution: (a) Renewable sources of energy are those which (i) can be replaced as we use them and (ii) can be used to produce energy again and again. Non-renewable sources of energy are those which cannot be replaced once these are used. (b) Exhaustible sources of energy are those whose supply is li...
Read More →Fill in the blanks using the correct option given in the bracket:
[question] Question. Fill in the blanks using the correct option given in the bracket: (i) Employment in the service sector _________ increased to the same extent as production. (has / has not) (ii) Workers in the _________ sector do not produce goods. (tertiary / agricultural) (iii) Most of the workers in the _________ sector enjoy job security. (organised / unorganised) (iv) A _________ proportion of labourers in India are working in the unorganised sector. (large / small) (v) Cotton is a ____...
Read More →Describe with the help of a diagram,
[question] Question. Describe with the help of a diagram, how compressions and rarefactions are produced in air near a source of sound. [/question] [solution] Solution: When a vibrating body like a tuning fork moves forward, it creates a region of high pressure in its vicinity. This region of high pressure is known as compression. When it moves backward, it creates a region of low pressure in its vicinity. This region is known as a rarefaction. As the body continues to move forward and backward,...
Read More →What are the limitations of extracting energy from
[question] Question. What are the limitations of extracting energy from (a) the wind (b) waves (c) tides ? [/question] [solution] solution: (a) Limitations of Wind Energy (1) The wind is very unpredictable, destructive source of energy. (2) It is not steady and consistent at all places. Thus, it can be used at the places where it is available, with consistent and steady characteristics. Wind energy farms can be established only at those places where wind blows for the greater part of a year. (3)...
Read More →The following table shows the proportion of undernourished adults in India.
[question] Question. The following table shows the proportion of undernourished adults in India. It is based on a survey of various states for the year 2001. Look at the table and answer the following questions. (i) Compare the nutritional level of people in Kerala and Madhya Pradesh. (ii) Can you guess why around 40 per cent of people in the country are undernourished even though it is argued that there is enough food in the country? Describe in your own words. [/question] [solution] Solution: ...
Read More →Compare and contrast fossil fuels and
[question] Question. Compare and contrast fossil fuels and the Sun as sources of energy [/question] [solution] solution: (1) The reserves of fossil fuels are limited i.e., exhaustible and they have high cost. But, solar energy is available in abundance i.e., it is inexhaustible and that too, without any cost. (2) Fossils fuels cause air pollution on burning whereas solar energy is pollution-free. (3) Fossil fuels can provide energy at any required time whereas solar energy is not available every...
Read More →What is the sound and how it is produced?
[question] Question. What is the sound and how it is produced? [question] [solution] Solution: Sound is a form of energy which produces sensation of hearing. When an object is set into vibrations, sound is produced. [solution]...
Read More →Give the characteristics and effects of the monsoon rainfall in India.
[question] Question. Give the characteristics and effects of the monsoon rainfall in India. [/question] [solution] Solution: Characteristics of monsoon rainfall in India: (i) The duration of the monsoon is between 100 to 120 days from early June to mid-September. (ii) Around the time of its arrival, the normal rainfall increases suddenly and continues for several days. This is known as the ‘burst’ of the monsoon. (iii) The monsoon has characteristic wet and dry spells or ‘breaks’ in rainfall. Th...
Read More →For each of the items given in Table 1.6, find out which country is at the top and which is at the bottom.
[question] Question. For each of the items given in Table 1.6, find out which country is at the top and which is at the bottom. [/question] [solution] Solution: Table 1.6 (i) Per Capita Income in US$: Top country - Sri Lanka; Bottom country - Myanmar (ii) Life Expectancy at birth: Top country - Sri Lanka; Bottom country - Myanmar (iii) Literacy Rate for 15+ yrs population: Top country - Sri Lanka; Bottom country - Bangladesh (iv) Gross Enrolment Ratio for three levels: Top country - Sri Lanka; B...
Read More →Most of the sources of energy we use represent stored solar energy.
[question] Question. Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun's energy ? (a) geothermal energy (b) wind energy (c) fossil fuels (d) bio-mass [/question] [solution] solution: Option (a) geothermal energy is correct. [/solution]...
Read More →A submarine emits a sonar pulse,
[question] Question. A submarine emits a sonar pulse, which returns from an underwater cliff in $1.02 \mathrm{~s}$. If the speed of sound in salt water is $1531 \mathrm{~ms}^{-1}$, how far away is the cliff ? [question] [solution] Solution: Given, time taken by the sonar pulse, $\mathrm{t}=1.02 \mathrm{~s}$; speed of sound in salt water, $\mathrm{v}=1531 \mathrm{~m} \mathrm{~s}^{-}$ 1 ; distance of cliff, $\mathrm{s}=?$ Now, $s=\frac{v}{2}=\frac{1531 \quad 1.02}{2}=780.81 \mathrm{~m}$ [solution]...
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