You must have seen weather reports on television and in newspapers.
[question] Question. You must have seen weather reports on television and in newspapers. How do you think we are able to predict the weather? [/question] [solution] Solution: The meteorological department of the government collects data on the elements of weather such as maximum and minimum temperatures, maximum and minimum humidity, rainfall, wind speed, etc. They are able to study these elements using various instruments. The maximum and minimum temperature of a day is measured by a thermomete...
Read More →Choose the most appropriate option.
[question] Question. Choose the most appropriate option. (i) The past two decades of globalisation has seen rapid movements in (a) goods, services and people between countries. (b) goods, services and investments between countries. (c) goods, investments and people between countries. (ii) The most common route for investments by MNCs in countries around the world is to (a) set up new factories. (b) buy existing local companies. (c) form partnerships with local companies. (iii) Globalisation has ...
Read More →How are living organisms dependent on the soil?
[question] Question. How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource? [/question] [solution] Solution: Almost all living organisms are dependent on soil. Some depend directly, while some depend indirectly. Plants need soil for getting support as well as nutrients to prepare their food. On the other hand, organisms depend on plants for food and other substances that are essential for life. Herbivores depend directly upon p...
Read More →Formulate the following problems as a pair of linear equations, and hence find their solutions:
[question] Question. Formulate the following problems as a pair of linear equations, and hence find their solutions: (i) Ritu can row downstream 20 km in 2 hours, and upstream 4 km in 2 hours. Find her speed of rowing in still water and the speed of the current. (ii) 2 women and 5 men can together finish an embroidery work in 4 days, while 3 women and 6 men can finish it in 3 days. Find the time taken by 1 woman alone to finish the work, and also that taken by 1 man alone. (iii)Roohi travels 300...
Read More →Why is water essential for life?
[question] Question. Why is water essential for life? [/question] [solution] Solution: Water is essential for life because of the following reasons :- (i) Most biological reactions occur when substances are dissolved in water. Thus, all cellular processes need water as a medium to take place. (ii) Transportation of biological substances needs water as a medium. [/solution]...
Read More →Match the following.
[question] Question. Match the following. [/question] [solution] Solution: [/solution]...
Read More →Why is the atmosphere essential for life?
[question] Question. Why is the atmosphere essential for life? [/question] [solution] Solution: The atmosphere is essential for life because it maintains an appropriate climate for the sustenance of life by carrying out the following activities: (i) Atmosphere keeps the average temperature of the Earth fairly constant during day time. (ii) It prevents a sudden increase in temperature during day time. (iii) It also slows down the escape of heat from the surface of the Earth into outer space durin...
Read More →A book with many printing errors contains four different
[question] Question. A book with many printing errors contains four different formulas for the displacement y of a particle undergoing a certain periodic motion: (a) $y=a \sin \left(\frac{2 \pi t}{T}\right)$ (b) $y=a \sin v t$ (c) $y=\left(\frac{a}{T}\right) \sin \frac{t}{a}$ (d) $y=(a \sqrt{2})\left(\sin \frac{2 \pi t}{T}+\cos \frac{2 \pi t}{T}\right)$ (a = maximum displacement of the particle, v = speed of the particle. T = time-period of motion). Rule out the wrong formulas on dimensional gro...
Read More →Fill in the blanks.
[question] Question. Fill in the blanks. Indian buyers have a greater choice of goods than they did two decades back. This is closely associated with the process of ______________. Markets in India are selling goods produced in many other countries. This means there is increasing ______________ with other countries. Moreover, the rising number of brands that we see in the markets might be produced by MNCs in India. MNCs are investing in India because _____________. While consumers have more choi...
Read More →What are the two forms of oxygen found in the atmosphere?
[question] Question. What are the two forms of oxygen found in the atmosphere? [/question] [solution] Solution: The two forms of oxygen found in the atmosphere are: (i) Diatomic molecular form with chemical formula $\mathrm{O}_{2}$. (ii) Triatomic molecular form with chemical formula $\mathrm{O}_{3}$ known as ozone. [/solution]...
Read More →Solve the following pairs of equations by reducing them to a pair of linear equations :
[question] Question. Solve the following pairs of equations by reducing them to a pair of linear equations : (i) $\frac{1}{2 x}+\frac{1}{3 y}=2, \frac{1}{3 x}+\frac{1}{2 y}=\frac{13}{6}$ (ii) $\frac{2}{\sqrt{x}}+\frac{3}{\sqrt{y}}=2, \frac{4}{\sqrt{x}}-\frac{9}{\sqrt{y}}=-1$ (iii) $\frac{4}{x}+3 y=14, \frac{3}{x}-4 y=23$ (iv) $\frac{5}{(x-1)}+\frac{1}{(y-2)}=2, \frac{6}{(x-1)}-\frac{3}{(y-2)}=1$ (v) $\frac{7 x-2 y}{x y}=5, \frac{8 x+7 y}{x y}=15$ (vi) $6 x+3 y=6 x y, 2 x+4 y=5 x y$ (viii) $\frac...
Read More →What is the greenhouse effect?
[question] Question. What is the greenhouse effect? [/question] [solution] Solution: Some gases like carbon dioxide, methane, nitrous oxide prevent the escape of heat from the Earth's surface by trapping it. This increases the average temperature of the Earth. This is called the green house effect. An increase in the content of such gases would lead to a situation of global warming. [/solution]...
Read More →A physical quantity $P$ is related to four observables $a, b, c$ and $d$ as follows:
[question] Question. A physical quantity $P$ is related to four observables $a, b, c$ and $d$ as follows: $P=\frac{a^{3} b^{2}}{(\sqrt{c} d)}$ The percentage errors of measurement in $a, b, c$ and $d$ are $1 \%, 3 \%, 4 \%$ and $2 \%$, respectively. What is the percentage error in the quantity $P ?$ If the value of $P$ calculated using the above relation turns out to be $3.763$, to what value should you round off the result? [/question] [solution] solution: $P=\frac{a^{3} b^{2}}{(\sqrt{c} d)}$ $...
Read More →Supposing you find two people arguing: One is saying globalisation has hurt our country’s development.
[question] Question. Supposing you find two people arguing: One is saying globalisation has hurt our country’s development. The other is telling, globalisation is helping India develop. How would you respond to these organisations? [/question] [solution] Solution: Globalisation has hurt our country’s development because: firstly, it has led to the annihilation of small producers who face stiff competition from cheaper imports. Secondly, workers no longer have job security and are employed “flexi...
Read More →List any three human activities which would lead to an increase in the carbon dioxide content of air.
[question] Question. List any three human activities which would lead to an increase in the carbon dioxide content of air. [/question] [solution] Solution: (i) Burning of fuels in various processes like heating, cooking, transportation, and industry. (ii) Human induced forest fires (iii) The process of deforestation includes the cutting down of trees. This decreases the uptake of carbon dioxide for photosynthesis. Eventually, the content of carbon dioxide increases. [/solution]...
Read More →Globalisation will continue in the future.
[question] Question. Globalisation will continue in the future. Can you imagine what the world would be like twenty years from now? Give reasons for your answer. [/question] [solution] Solution: Globalisation will continue in the future. Twenty years from now, the world will be more globally connected and integrated into one international economy, if this process continues on a fair and equitable basis. Trade and capital flows will increase alongside the mobility of labour. This will occur becau...
Read More →The mass of a box measured by a grocer’s balance is 2.300 kg.
[question] Question. The mass of a box measured by a grocer’s balance is 2.300 kg. Two gold pieces of masses 20.15 g and 20.17 g are added to the box. What is (a) the total mass of the box, (b) the difference in the masses of the pieces to correct significant figures? [/question] [solution] solution: Mass of grocer’s box = 2.300 kg Mass of gold piece I = 20.15g = 0.02015 kg Mass of gold piece II = 20.17 g = 0.02017 kg (a) Total mass of the box = 2.3 + 0.02015 + 0.02017 = 2.34032 kg In addition, ...
Read More →Name two biologically important compounds that contain both oxygen and nitrogen.
[question] Question. Name two biologically important compounds that contain both oxygen and nitrogen. [/question] [solution] Solution: Two biologically important compounds that contain both oxygen and nitrogen are: (i) Amino acids (ii) Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA) [/solution]...
Read More →What are the different states in which water is found during the water cycle?
[question] Question. What are the different states in which water is found during the water cycle? [/question] [solution] Solution: During the water cycle, water is found in solid state (snow, ice, etc.), liquid state (ground water, river water, etc.), and gaseous state (water vapours). [/solution]...
Read More →What are the methods of preventing or reducing soil erosion?
[question] Question. What are the methods of preventing or reducing soil erosion? [question] [solution] Solution: The methods of preventing or reducing soil erosion are : (i) Prevention of deforestation (ii) Plantation of trees...
Read More →How does foreign trade lead to integration of markets across countries?
[question] Question. How does foreign trade lead to integration of markets across countries? Explain with an example other than those given here. [/question] [solution] Solution: Foreign trade leads to integration of markets across countries by the processes of imports and exports. Producers can make available their goods in markets beyond domestic ones via exports. Likewise, buyers have more choice on account of imports from other countries. This is how markets are integrated through foreign tr...
Read More →What is soil erosion?
[question] Question. What is soil erosion? [/question] [solution] Solution: The blowing away or washing away of land surface by wind or water is known as soil erosion. [/solution]...
Read More →The length, breadth and thickness of a rectangular sheet of metal
[question] Question. The length, breadth and thickness of a rectangular sheet of metal are $4.234 \mathrm{~m}, 1.005 \mathrm{~m}$, and $2.01 \mathrm{~cm}$ respectively. Give the area and volume of the sheet to correct significant figures. [/question] [solution] solution: Length of sheet, $I=4.234 \mathrm{~m}$ Breadth of sheet, $b=1.005 \mathrm{~m}$ Thickness of sheet, $h=2.01 \mathrm{~cm}=0.0201 \mathrm{~m}$ The given table lists the respective significant figures: Hence, area and volume both mu...
Read More →How is soil formed?
[question] Question. How is soil formed? [/question] [solution] Solution: Soil is formed by breaking down of rocks at or near the surface of the Earth through various physical, chemical, and biological processes by various factors such as the sun, water, wind, and living organisms. (i) Sun : During day time, the rocks are heated. This causes the rocks to expand. During night time, these rocks cool down and contract. Since all parts of the rock do not undergo expansion and contraction at the same...
Read More →How has liberalisation of trade and investment policies
[question] Question. How has liberalisation of trade and investment policies helped the globalisation process? [/question] [solution] Solution: Liberalisation of trade and investment policies has helped the globalisation process by making foreign trade and investment easier. Earlier, several developing countries had placed barriers and restrictions on imports and investments from abroad to protect domestic production. However, to improve the quality of domestic goods, these countries have remove...
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