A girl stands on a box having 60cm length,
Question: A girl stands on a box having $60 \mathrm{~cm}$ length, $40 \mathrm{~cm}$ breadth and $20 \mathrm{~cm}$ width in three ways. In which of the following cases, pressure exerted by the brick will be (a) maximum when length and breadth form the base (b) maximum when breadth and width form the base (c) maximum when width and length form the base (d) the same in all the above three cases. Solution: (b). Explanation: $P=\frac{F}{A}$...
Read More →An obj ect weighs 10 N in air.
Question: An obj ect weighs $10 \mathrm{~N}$ in air. When immersed fully in water, it weighs only $8 \mathrm{~N}$. The weight of the liquid displaced by the object will be (a) $2 \mathrm{~N}$ (b) $8 \mathrm{~N}$ (c) $10 \mathrm{~N}$ (d) $12 \mathrm{~N}$. Solution: (a). Explanation: Weight of liquid displaced by an object = Weight of object in air - weight in liquid....
Read More →An object is put one by one in three liquids having different densities.
Question: An object is put one by one in three liquids having different densities. The object floats with $1 / 9,2 / 11$ and $3 / 7$ parts of their volumes outside the liquid surface in liquids of densities $d_{1}, d_{2}$ and $d_{3}$ respectively. Which of the following statement is correct? (a) $d_{1}d_{2}d_{3}$ (b) $d_{1}d_{2}d_{3}$ (c) $d_{1}d_{2}d_{3}$ (d) $d_{1}d_{2}d_{3}$ Solution: (d). Upthrust due to liquid on an object is directly proportional to the density of the liquid....
Read More →Evaluate :
Question: Evaluate : $\left|\begin{array}{ccc}1 a b c \\ 1 b c a \\ 1 c a b\end{array}\right|$ Solution: $\Delta=\left|\begin{array}{ccc}1 a b c \\ 1 b c a \\ 1 c a b\end{array}\right|$ When $a=b$, the first two rows become identical. Hence, $a-b$ is a factor. Similarly, when $b=c$ and $c=a$, the second and third and third and first rows become identical. Hence, $b-c$ and $c-a$ are also factors The degree of product of the diagonal elements is 3 . Hence, there are no other factors. $\left|\begin...
Read More →Evaluate :
Question: Evaluate : $\left|\begin{array}{ccc}1 a b c \\ 1 b c a \\ 1 c a b\end{array}\right|$ Solution: $\Delta=\left|\begin{array}{ccc}1 a b c \\ 1 b c a \\ 1 c a b\end{array}\right|$ When $a=b$, the first two rows become identical. Hence, $a-b$ is a factor. Similarly, when $b=c$ and $c=a$, the second and third and third and first rows become identical. Hence, $b-c$ and $c-a$ are also factors The degree of product of the diagonal elements is 3 . Hence, there are no other factors. $\left|\begin...
Read More →The figure shows two crop fields (plots A and B)
Question: The figure shows two crop fields (plots A and B) have been treated by manures and chemical fertilizers respectively, keeping other environmental factors same. Observe the graph and answer the following questions: 1. Why does plot B show sudden increase and then gradual decrease in yield? 2. Why is the highest peak in plot A graph slightly delayed? 3. What is the reason for the different pattern of the two graphs. Solution: 1. Sudden Increase: Chemical fertilizer supplies the minerals i...
Read More →Evaluate :
Question: Evaluate : $\left|\begin{array}{lll}a b+c a^{2} \\ b c+a b^{2} \\ c a+b c^{2}\end{array}\right|$ Solution: $\Delta=\left|\begin{array}{lll}a b+c a^{2} \\ b c+a b^{2} \\ c a+b c^{2}\end{array}\right|$ When $a=b$, the first two rows become identical. Hence, $a-b$ is a factor. Similarly, when $b=c$ the second and third rows become identical. So, $b-c$ is also a factor. Also, when $c=a$, the third and first rows become identical. Hence, $c-a$ is also a factor. The product of diagonal eleme...
Read More →Suggest some preventive measures
Question: Suggest some preventive measures for the diseases of poultry birds. Solution: 1. The poultry birds should be kept in good spacious, airy and ventilated shelter. 2. The shelter should be cleaned properly and regularly. Quick and hygienic disposal of excreta should be ensured. 3. External parasites should be controlled, preferably by applying dilute insecticide solution. Disinfectant should be sprayed to kill mosquitoes and other external parasites. 4. Every animal should be vaccinated t...
Read More →What would happen if poultry birds are larger in
Question: What would happen if poultry birds are larger in size and have no summer adaptation capacity ? In order to get small sized poultry birds having summer adaptability, what methods will be employed? Solution: Larger sized birds require more feed. Summer adaptation is connected with egg laying. Little summer adaptation reduces egg laying. In order to obtain small sized poultry birds having summer adaptability, it is desirable to 1. Either introduce the required exotic birds from outside an...
Read More →Name two types of animal feed and write their functions.
Question: Name two types of animal feed and write their functions. Solution: 1. The sick animal looks tired. It becomes inactive and tries to remain isolated. 2. There is little interest in taking food. 3. The animal moves slowly, limping well behind others in the herd. 4. The milk yield, egg laying capacity or working capacity of the animal is reduced drastically. 5. The animal passes loose or watery dung. 6. Urine may become coloured. 7. Eyes may turn red. 8. Ears may droop. 9. There may be wh...
Read More →Without expanding, show that the values of each of the following determinants are zero:
Question: Without expanding, show that the values of each of the following determinants are zero: (i) $\left|\begin{array}{ccc}8 2 7 \\ 12 3 5 \\ 16 4 3\end{array}\right|$ (ii) $\left|\begin{array}{ccc}6 -3 2 \\ 2 -1 2 \\ -10 5 2\end{array}\right|$ (iii) $\left|\begin{array}{ccc}2 3 7 \\ 13 17 5 \\ 15 20 12\end{array}\right|$ (iv) $\left|\begin{array}{ccc}1 / a a^{2} b c \\ 1 / b b^{2} a c \\ 1 / c c^{2} a b\end{array}\right|$ (v) $\left|\begin{array}{ccc}a+b 2 a+b 3 a+b \\ 2 a+b 3 a+b 4 a+b \\ ...
Read More →Discuss why pesticides are used in very accurate
Question: Discuss why pesticides are used in very accurate concentration and in very appropriate manner? Solution: Pesticides should not be used indiscriminately. Only very accurate dose should be applied at appropriate time. Even slight excess of the pesticide is extremely harmful. 1. Pesticides are harmful to soil biota. Therefore, they reduce soil fertility. 2. They pass into ground water and make it toxic. 3. They enter the crop plants and make them toxic. 4. Pesticides pass into surface wat...
Read More →Write the modes by which insects affect the crop yield.
Question: Write the modes by which insects affect the crop yield. Solution: The important types of crops are : 1. Cereal Crops (Grain Crops): Wheat, rice, maize, (major cereals), barley, sorghum, minor millets (minor cereals). They are rich source of carbohydrates that meet the energy requirement of body. Other useful ingredients are dietary fibres, proteins, vitamins and minerals. 2. Pulses (Legume Seeds): Gram (chana), pea (matar), black gram (urad), green gram (moong), pigeon pea (arhar), len...
Read More →Why bee keeping should be done in good pasturage?
Question: Why bee keeping should be done in good pasturage? Solution: Pasturage/Crop/Flora: Quality, taste and quantity of honey depend upon the flora or pasturage available for nectar and pollen collection. Pasturage is different in different geographical regions and locations, plains and mountains. The best honey is almond honey of Kashmir....
Read More →What do you understand by composite fish culture?
Question: What do you understand by composite fish culture? Solution: Composite culture is highly advantageous: 1. These fishes do not compete with one another for food because they have different types of food habits. 2. The food available in all the zones (parts) of the pond is utilized due to their food habits. 3. The carps consume only natural foods. 4. Six different types of fish are reared in the same pond. 5. The yield is very high....
Read More →Give merits and demerits of fish culture.
Question: Give merits and demerits of fish culture. Solution: Merits: 1. Desired Fish: Economically important desired fishes are made available. 2. Smaller Area: A large number of fishes are raised in a small area. 3. Fish Seeding: Fishes are made to breed in different seasons. 4. Mortality: There is little mortality in the younger stages of the fishes. 5. Improvement: Through selective hybridisation, yield and quality of fishes are improved. Demerits: 1. Genetic Loss: Only some selected high yi...
Read More →Differentiate between the following:
Question: Differentiate between the following: (i) Capture fishery and culture fishery (CCE 2011, 2012) (ii) Mixed cropping and inter cropping (iii) Bee keeping and poultry farming. Solution: (i) Differences between Capture Fishery and Culture Fishery (ii) Differences between Mixed Cropping and Intercropping....
Read More →Discuss various methods of weed control.
Question: Discuss various methods of weed control. Solution: Mechanical Methods: 1. Removal of weeds by pulling them out with hand. 2. Removal of weeds by using trowel (khurpa). 3. Removal of weeds by ploughing, burning and flooding before sowing. 4. Removal of weeds by interculture. Cultural Methods : 1. Timely sowing of crops. 2. Proper seed bed preparation 3. Intercropping 4. Crop rotation Chemical Methods: Destroying the weeds by spraying special chemicals called weedicides like, $2,4-D(2,4$...
Read More →Prove the following
Question: Define 1. Vermicompost 2. Green Manure 3. Biofertilizers. Solution: 1. Vermicompost: It is a manure rich in pulverised organic matter and worm castings. Vermicompost is formed by the activity of earth worms on organic remains. 2. Green Manure: It is manure formed inside soil from young green crop plants ploughed hack into soil. The green manure crops are generally quick growing legume crops which are mulched by ploughing them back into field in tender stage (about $6-8$ weeks) only, ge...
Read More →Discuss the role of hybridisation in crop improvement.
Question: Discuss the role of hybridisation in crop improvement. Solution: 1. Choice of Parents: Two older varieities of crop having different desirable characteristics, are selected. For example, if we want to obtain a variety having higher yield as well as disease resistance, we should select two existing varieties of crops, one having higher yield and the other having more resistance to diseases. 2. Cross-breeding: The Two Parents. Pollen grains of plants of one variety are dusted over the st...
Read More →In agricultural practices, higher input gives higher yield. Discuss how?
Question: In agricultural practices, higher input gives higher yield. Discuss how? Solution: In agriculture, higher yield can be obtained only by employing higher yielding varieties, improved farming practices, modern technology, latest agricultural machines and implements, nutrient supply, etc. All these require high cost and knowledge of new techniques and improvements. Therefore, a farmer's purchasing capacity for inputs determines the cropping system and production practices....
Read More →An Italian bee variety A melliftra has been
Question: An Italian bee variety A melliftra has been introduced in India for honey production. Write about its merits over other varieties. Solution: There are three common species of honey bees in our country used for commercial production of honey. These are 1. Apis cerana indica - Indian Bee 2. Apis dorsata - Rock Bee 3. Apis florae (A. florea) - Little Bee To produce honey at commercial level, the Italian variety of honey bee \{Apis mellifera) is commonly used. This variety is domesticated ...
Read More →Arrange these statements in correct sequence of preparation of green manure.
Question: Arrange these statements in correct sequence of preparation of green manure. (a) Green plants are decomposed in soil. (b) Green plants are cultivated for preparing manure or crop plant parts are used. (c) Plants are ploughed and mixed in soil. (d) After decomposition, it becomes green manure. Solution: $(b)(c)(a)(d)$...
Read More →Differentiate between compost and vermicompost.
Question: Differentiate between compost and vermicompost. Solution:...
Read More →Fill in the blanks :
Question: Fill in the blanks : (a) A total of . nutrients are essential to plants. (b) and . are supplied by air to plants. (c) . is supplied by water to plants. (d) Soil supplies . nutrients to plants. (e) .. nutrients are required in large quantity and called as (f) .. nutrients are needed in small quantity for plants and are called . Solution: (a) 16 (b) Carbon, oxygen (c) Hydrogen (d) 13 (e) six, macronutrients (f) seven, micronutrients....
Read More →