Fertile soil has lots of hurpus.
Question: Fertile soil has lots of hurpus. Why? (CCE 2012) Solution: Fertile soils possess lots of humus because 1. Humus is required for binding soil particles into crumbs. Crumb formation is needed for both hydration and aeration of soil, 2. Humus makes the soil porous for easy passage of roots, 3. It is source of minerals. 4. Humus contains chemicals that promote growth of plants....
Read More →"Soil is formed by water".
Question: "Soil is formed by water". If you agree with this statement, then give reasons. Solution: Yes, "action of water in weathering" (wetting and drying, frost action, abrasion). 1. Wetting and Drying. Certain rock components can pick up and lose moisture. They undergo swelling and contraction resulting in fragmentation of rocks. 2. Frost Action. Water seeping in cracks would swell up and exert a great pressure if it freezes due to low temperature. The rock would undergo fragmentation. 3. Ru...
Read More →Find the values of x, if
Question: Find the values ofx, if (i) $\left|\begin{array}{ll}2 4 \\ 5 1\end{array}\right|=\left|\begin{array}{cc}2 x 4 \\ 6 x\end{array}\right|$ (ii) $\left|\begin{array}{ll}2 3 \\ 4 5\end{array}\right|=\left|\begin{array}{cc}x 3 \\ 2 x 5\end{array}\right|$ (iii) $\left|\begin{array}{ll}3 x \\ x 1\end{array}\right|=\left|\begin{array}{ll}3 2 \\ 4 1\end{array}\right|$ (iv) If $\left|\begin{array}{cc}3 x 7 \\ 2 4\end{array}\right|=10$, find the value of $x$ (v) $\left|\begin{array}{ll}x+1 x-1 \\ ...
Read More →Lichens are called pioneer colonisers of bare rock.
Question: Lichens are called pioneer colonisers of bare rock. How can they help in formation of soil? Solution: Ans. Lichens release small quantity of acids which corrode the surface of rocks creating small pores and releasing minerals. With the passage of time the porous surface changes into thin layer of soil....
Read More →There is a mass mortality of fish in a pond.
Question: There is a mass mortality of fish in a pond. What may be the reasons? Solution: 1. Passage of pesticide rich water from crop fields., 2. Pouring of industrial waste. 3. Pouring of hot water from an industry or thermal power plant. 4. Release of waste rich in heavy metal and mercury. 5. Blockage of fish gills by some suspended pollutant. 6. Excessive eutrophication....
Read More →Wliy does water need conservation
Question: Wliy does water need conservation even though large oceans surround the land masses? (CCE 2012) Solution: Marine water is unfit for consumption by humans, industries or land plants and animals. Therefore, terrestrial biota and human beings have to depend upon fresh water resources available on land (only about $0.5 \%$ of the total). The same has to be conserved....
Read More →Why do not lichens occur in Delhi/Mumbai whereas
Question: Why do not lichens occur in Delhi/Mumbai whereas they commonly grow in Manali/Ooty or Darjeeling? (CCE 2011, 2012) Solution: Lichens are sensitive to sulphur dioxide which occurs in sufficient quantity in the atmosphere of Delhi due to large number of vehicles, homes and factories using fossil fuels. Moreover, Delhi occurs in semi-arid area where, atmospheric moisture is low. In Manali and Darjeeling, the atmosphere is humid and sulphur dioxide pollution is comparatively low....
Read More →Wliy does Mathura refinery pose
Question: Wliy does Mathura refinery pose problems to the Taj Mahal ? (CCE 2014) Solution: Mathura refinery emits hydrocarbons and sulphur oxides. Hydrocarbons induce the formation of ozone which is highly oxidising. Sulphur dioxide produces acid rain which has a corroding effect on marble. Therefore, Mathura refinery does pose problems to Taj Mahal....
Read More →Why do people love to fly
Question: Why do people love to fly kites near the sea shore? (CCE2012) Solution: 1. There is a regular unidirectional wind from sea to land. 2. It helps in flying the kite high. 3. The wind is cooler and provides comfort even in bright sun....
Read More →Solve the following equations
Question: If $A\left[\begin{array}{lll}1 0 1 \\ 0 1 2 \\ 0 0 4\end{array}\right]$, then show that $|3 A|=27|A|$. Solution: $A=\left[\begin{array}{lll}1 0 1 \\ 0 1 2 \\ 0 0 4\end{array}\right]$ $\Rightarrow 3 A=\left[\begin{array}{ccc}3 0 3 \\ 0 3 6 \\ 0 0 12\end{array}\right]$ [Multiplying each element of A by 3 ] $\Rightarrow|3 A|=(-1)^{1+1} 3(36-0)+(-1)^{1+2} 0(0-0)+(-1)^{1+3} 3(0-0)=3(36-0)-0(0-0)+3(0-0) \quad\left[\right.$ Expanding along $\left.R_{1}\right]$ $=3 \times 36=108$ $\ldots(1)$ $...
Read More →Why has moon very cold and very high
Question: Why has moon very cold and very high temperature variations, e.g., from $-190^{\circ} \mathrm{C}$ to $110^{\circ} \mathrm{C}$ even though it is at the same distance from the sun as the earth is? (CCE 2012) Solution: Moon does not possess atomosphere. Atmosphere being a bad conductor acts as a temperature buffer on earth. This is not so on the moon. Therefore, moon gets heated up as the sun rays fall on its surface. It cools down drastically when there is no sunlight....
Read More →Why does the percentage of gases like oxygen,
Question: Why does the percentage of gases like oxygen, nitrogen and carbon dioxide remain almost the same in the atmosphere? Solution: Through biogeochemical cycling where there is repeated circulation of biogenetic nutrients between abiotic and biotic components of the environment....
Read More →All the living organisms are basically made
Question: All the living organisms are basically made up of $\mathrm{C}, \mathrm{N}, \mathrm{S}, \mathrm{P}, \mathrm{H}$ and $\mathrm{O}$. How do they enter the living forms ? Discuss. Solution: Most of them first enter plants and become components of organic materials during the process of photosynthesis. They enter plants from air $\left(\mathrm{CO}_{2}\right)$, water and ions (from soil). From plants the chemicals pass on to other organisms....
Read More →Soil formation is done by both abiotic and biotic factors.
Question: Soil formation is done by both abiotic and biotic factors. List the name of these factors by classifying them as abiotic and biotic. (CCE 2012) Solution: Abiotic Factors : Sun, water, wind. Biotic Factors : Lichens, mosses, herbs, shrubs and trees....
Read More →Solve this
Question: If $A=\left[\begin{array}{ll}2 5 \\ 2 1\end{array}\right]$ and $B=\left[\begin{array}{cc}4 -3 \\ 2 5\end{array}\right]$, verify that $|A B|=|A||B|$. Solution: Consider LHS $A B=\left[\begin{array}{ll}2 5 \\ 2 1\end{array}\right]\left[\begin{array}{cc}4 -3 \\ 2 5\end{array}\right]$ $=\left[\begin{array}{cc}8+10 -6+25 \\ 8+2 -6+5\end{array}\right]=\left[\begin{array}{cc}18 19 \\ 10 -1\end{array}\right]$ $|A B|=-18-190=-208$ Consider RHS $|A|=2-10=-8$ $|B|=20-(-6)=26$ $|A||B|=-8 \times 26...
Read More →Following are a few organisms :
Question: Following are a few organisms : (a) Lichens (b) Mosses (c) Mango tree (d) Cactus. Which among the above can grow on stones and also help in formation of soil ? Write the mode of their action for making soil. Solution: Lichens and Mosses. Weathering by Living Organisms: Living Organisms are cause biological weathering. Lichens growing on rock surface are able to extract minerals from the same. This produces small crevices where a thin layer of soil builds up. Mosses grow over these crev...
Read More →In coastal area, wind current moves from
Question: In coastal area, wind current moves from sea towards the land during day but during night it moves from land to the sea. Discuss the reason. Solution: Air Movement in Coastal Areas: In coastal areas, there is a regular flow of cooler air from sea towards the land during the daytime. It is because during the daytime land gets heated faster than water. Reradiation from land heats the air above it. The hot air rises and creates an area of low pressure. Sea water is not heated so rapidly. ...
Read More →Solve the following equations
Question: $\Delta=\left|\begin{array}{ccc}\cos \alpha \cos \beta \cos \alpha \sin \beta -\sin \alpha \\ -\sin \beta \cos \beta 0 \\ \sin \alpha \cos \beta \sin \alpha \sin \beta \cos \alpha\end{array}\right|$ Solution: Given: $\Delta=\left|\begin{array}{ccc}\cos \alpha \cos \beta \cos \alpha \sin \beta -\sin \alpha \\ -\sin \beta \cos \beta 0 \\ \sin \alpha \cos \beta \sin \alpha \sin \beta \cos \alpha\end{array}\right|$ $\Rightarrow \Delta=(-1)^{1+1} \cos \alpha \cos \beta(\cos \alpha \cos \bet...
Read More →During summer, if you go near the lake,
Question: During summer, if you go near the lake, you feel relief from heat. Why? Solution: During day time, air over the land becomes heated up, rises upward and creates an area of low pressure. Lake water is not heated up so quickly. Evaporation of water from its surface also cools it up. Therefore, air over the surface of lake is cooler. It moves towards the land where low pressure exists. Therefore, during day dme a cool breeze flows from lake to the land nearby....
Read More →How is the life of organisms living
Question: How is the life of organisms living in water affected when water gets polluted ? (CCE 2012) Solution: Water gets polluted from domestic wastes, fertilizers, pesticides (from fields) and industrial wastes. 1. Fertilizers and domestic wastes cause eutrophication or excessive growth and increased organic loading. This, reduces oxygen available to aquatic animals, 2. Domestic waste carries pathogens of a number of diseases. Some of them can cause diseases in aquatic animals as well, 3. Pes...
Read More →How can we prevent loss of top soil?
Question: How can we prevent loss of top soil? Solution: Control of Soil Erosion: Soil erosion can be prevented by providing plant cover to soil. Roots of plants hold the soil firmly around them. They increase water percolation during rains and decrease runoff. Vegetation cover also reduces direct pounding of soil by rain drops. The various methods to control soil erosion are as follows: 1. Vegetation Cover: Soil should not be left uncovered. Tree plantation should be undertaken where vegetation...
Read More →Rivers from land, add minerals to sea water.
Question: Rivers from land, add minerals to sea water. Discuss how. Solution: Rivers are formed from springs, melting snow and rain water flowing over land as run off. While, passing through and over the rocks, the flowing water picks up minerals. These dissolved minerals are taken by rivers to sea and make them available to marine organisms....
Read More →Solve the following Matrix
Question: Evaluate $\Delta=\left|\begin{array}{ccc}0 \sin \alpha -\cos \alpha \\ -\sin \alpha 0 \sin \beta \\ \cos \alpha -\sin \beta 0\end{array}\right|$ Solution: Let $\Delta=\left|\begin{array}{ccc}0 \sin \alpha -\cos \alpha \\ -\sin \alpha 0 \sin \beta \\ \cos \alpha -\sin \beta 0\end{array}\right|$ $\Delta=(-1)^{1+1} 0\left(0+\sin ^{2} \beta\right)+(-1)^{1+2} \sin \alpha(0-\sin \beta \cos \alpha)+(-1)^{1+3}(-\cos \alpha)(\sin \alpha \sin \beta-0) \quad\left[\right.$ Expanding along $\left.R...
Read More →Solve this
Question: Evaluate $\left|\begin{array}{ccc}2 3 -5 \\ 7 1 -2 \\ -3 4 1\end{array}\right|$ by two methods. Solution: Let $\Delta=\left|\begin{array}{ccc}2 3 -5 \\ 7 1 -2 \\ -3 4 1\end{array}\right|$ First method $\Delta=(-1)^{1+1} 2(1+8)+(-1)^{1+2} 3(7-6)+(-1)^{1+3}(-5)(28+3)$ $=2(1+8)-3(7-6)-5(28+3)$ $=18-3-155$ $=-140$ Second method is the Sarus Method, where we adjoin the first two columns to the right to get $\begin{array}{lllll}2 3 -5 2 3\end{array}$ $\begin{array}{lllll}7 1 -2 7 1\end{array...
Read More →Solve this
Question: Evaluate $\left|\begin{array}{ccc}2 3 -5 \\ 7 1 -2 \\ -3 4 1\end{array}\right|$ by two methods. Solution: Let $\Delta=\left|\begin{array}{ccc}2 3 -5 \\ 7 1 -2 \\ -3 4 1\end{array}\right|$ First method $\Delta=(-1)^{1+1} 2(1+8)+(-1)^{1+2} 3(7-6)+(-1)^{1+3}(-5)(28+3)$ $=2(1+8)-3(7-6)-5(28+3)$ $=18-3-155$ $=-140$ Second method is the Sarus Method, where we adjoin the first two columns to the right to get $\begin{array}{lllll}2 3 -5 2 3\end{array}$ $\begin{array}{lllll}7 1 -2 7 1\end{array...
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