The radius of curvature of a spherical
[question] Question. The radius of curvature of a spherical mirror is $20 \mathrm{~cm}$. What is its focal length ? [/question] [solution] solution: Given, radius of curvature, $R=20 \mathrm{~cm}$ Focal length, $\mathrm{f}=(1 / 2) \times$ radius of curvature or $\mathrm{f}=(1 / 2) \times \mathrm{R}=(1 / 2) \times 20=10 \mathrm{~cm}$ [/solution]...
Read More →Which of the following has more inertia :
[question] Question. Which of the following has more inertia : (a) a rubber ball and a stone of the same size ? (b) a bicycle and a train ? (c) a five rupees coin and a one-rupee coin ? [/question] [solution] Solution: Mass of a body is the measure of its inertia i.e., more the mass, more is the inertia. Keeping this in mind : (a) Stone has more inertia. (b) Train has more inertia. (c) Five rupees coin has more inertia. [/solution]...
Read More →Define the principal focus of a concave mirror.
[question] Question. Define the principal focus of a concave mirror. [/question] [solution] solution: The principal focus of a concave mirror is a point on the principal axis, at which the incident rays parallel to the principal axis, after reflection, actually meet. [/solution]...
Read More →An artificial satellite is moving in a circular orbit of radius
[question] Question. An artificial satellite is moving in a circular orbit of radius 42250 km. Calculate its speed if it takes 24 hours to revolve around the earth. [/question] [solution] Solution: Distance covered by the satellite in 24 hours. $S=2 \pi r$ $=2 \times \frac{22}{7} \times 42250$ $=265571.43 \mathrm{~km}$ Therefore speed of satellite $v=\frac{\text { distance travelled }}{\text { time taken }}=\frac{265571.43}{24 \times 60 \times 60}=3.07 \mathrm{kms}^{-1}$ [solution]...
Read More →Examine the following pairs that give the level of government in India and the
[question] Question. Examine the following pairs that give the level of government in India and the powers of the government at that level to make laws on the subjects mentioned against each. Which of the following pairs is not correctly matched? [/question] [solution] Solution: [/solution]...
Read More →State which of the following situations
[question] Question. State which of the following situations are possible and give an example for each of these: (a) An object with a constant acceleration but with zero velocity. (b) An object moving in a certain direction with acceleration in the perpendicular direction. [/question] [solution] Solution: (a)A body with a constant acceleration but with zero velocity is possible. For example, when a body is just released, its initial velocity u = 0, but acceleration g = 10 ms–2 (b)It is possible ...
Read More →The speed-time graph for a car is shown in figure below.
[question] Question. The speed-time graph for a car is shown in figure below. (a) Shade the area on the graph that represents the distance travelled by the car during the first 4 seconds. (b) Which part of the graph represents uniform motion of the car ? [/question] [solution] Solution: (a)During first 4 seconds, car is moving with non-uniform acceleration. Area of shaded portion represents distance travelled. (b)The straight line portion of the graph represents uniform motion of the car. [/solu...
Read More →Only variations that confer an advantage to an individual organism will survive in a population.
[question] Question. Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement ? Why or why not ? [/question] [solution] solution: No, many of the times the variations are not advantageous to an individual organism but they still survive in a population, e.g., take the case of free ear lobe and attached ear lobe. Most of the other variations not only give survival advantage to an individual but also contribute to genetic dri...
Read More →A few subjects in various Lists of the Indian Constitution are given here. Group them under the Union, State and Concurrent Lists as provided in the table below.
[question] Question. A few subjects in various Lists of the Indian Constitution are given here. Group them under the Union, State and Concurrent Lists as provided in the table below. A. Defence Β. Police C. Agriculture D. Education E. Banking F. Forests G. Communications H. Trade I. Marriages [/question] [solution] Solution: [/solution]...
Read More →How is the equal genetic contribution of male
[question] Question. How is the equal genetic contribution of male and female parents ensured in the progeny ? [/question] [solution] solution: Genetically organisms are of two types : (i) Haploid : They have single set of chromosomes, where each chromosome is represented singly. As the chromosomes are the bearer of genes so haploids have single set of genes. A single gene determine the expression of character. (ii) Diploid : They have two set of homologous chromosomes, where the chromosome occu...
Read More →A ball is gently dropped from a height of 20 m.
[question] Question. A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 ms–2, with what velocity will it strike the ground? After what time will it strike the ground ? [/question] [solution] Solution: Given, initial velocity of ball, $\mathrm{u}=0$ Final velocity of ball, $\mathrm{v}=?$ Distance through which the ball falls, $\mathrm{s}=20 \mathrm{~m}$ Acceleration $\mathrm{a}=10 \mathrm{~ms}^{-2}$ Time of fall, $\mathrm{t}=$ ? We know $v^{2}-u^...
Read More →Explain how sexual reproduction gives rise
[question] Question. Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually ? [/question] [solution] solution: Variations occurring during sexual reproduction may be due to : (i) Separation of homologous chromosomes (by chance only) during gamete formation, (ii) Crossing over (recombination) of homologous chromosomes. (iii) Fertilisation of gametes to form zygote. (iv) Errors du...
Read More →Figure below shows the distance-time graph of three objects
[question] Question. Figure below shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions : (a) Which of the three is travelling the fastest ? (b)Are all three ever at the same point on the road? (c) How far has C travelled when B passes A ? (d) How far has B travelled by the time it passes C ? [question] [solution] Solution: (a) Car B is travelling the fastest, because its slope is largest among the three. (b) No, they are never at the same ...
Read More →What evidence do we have for the origin
[question] Question. What evidence do we have for the origin of life from inanimate matter ? [/question] [solution] solution: B.S. Haldane suggested that life must have developed from the simple inorganic molecules which were present on earth soon after it was formed. He speculated that the conditions on earth at that time could have given rise to more complex organic molecules that were necessary for life. The first primitive organisms would arise from further chemical synthesis. Later on, Stan...
Read More →The distinguishing feature of a federal government is:
[question] Question. The distinguishing feature of a federal government is: (a) National government gives some powers to the provincial governments. (b) Power is distributed among the legislature, executive and judiciary. (c) Elected officials exercise supreme power in the government. (d) Governmental power is divided between different levels of government. [/question] [solution] Solution: (d) Governmental power is divided between different levels of government. [/solution]...
Read More →Explain the importance of fossils in deciding
[question] Question. Explain the importance of fossils in deciding evolutionary relationships. [/question] [solution] solution: Origin of life on this planet is a result of chemical evolution. It was followed by biological or organic evolution which gave rise to numerous type of living organisms over the age. Some of these organisms became fossilised and are helpful to trace the evolutionary relationship amongst living organisms. The discovery of some fossils provide missing links between two di...
Read More →Outline a project which aims to find the dominant coat colour in dogs.
[question] Question. Outline a project which aims to find the dominant coat colour in dogs. [/question] [solution] solution: Project: To find out the dominant coat colour in dogs. Material required: Notebook, pencil. Procedure: Observe different colour of pet dogs kept by your friends and note their different coat colour. You may be able to find different coat colours such as, grey, white, black, brown, etc. Note your reading in the observation table. Make a survey of different populations to de...
Read More →The driver of a car travelling at 52 km h–1 applies the brakes and accelerates uniformly in the opposite direction.
[question] Question. The driver of a car travelling at 52 km h–1 applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 kmh–1 in another car, applies his brakes slowly and stops in 10 s. On the same graph paper, plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied ? [/question] [solution] Solution: The speed time graph of both the cars are shown below. (i) Distanc...
Read More →Fill in the blanks:
[question] Question. Since the United States is a ____________________ type of federation, all the constituent States have equal powers and States are _______________ vis-à-vis the federal government. But India is a _________________ type of federation and some States have more power than others. In India, the ___________________ government has more powers. [/question] [solution] Solution: Since the United States is a coming together type of federation, all the constituent States have equal powe...
Read More →Explain the terms analogous and
[question] Question. Explain the terms analogous and homologous organs with examples. [/question] [solution] solution: Homologous organs are those organs having similar basic structure but has been modified to perform different functions, e.g., forelimbs of reptiles, frog, lizard, bird and human (amphibians and mammals) are homologous organs. Such homologous characteristic helps to identify an evolutionary relationship between apparently different species. Analogous organs are those organs which...
Read More →A motorboat starting from rest on a lake accelerates in a straight line at a constant rate of 3.0 ms–2 for 8.0 s.
[question] Question. A motorboat starting from rest on a lake accelerates in a straight line at a constant rate of 3.0 ms–2 for 8.0 s. How far does the boat travel during this time ? [/question] [solution] Solution: Given, initial velocity of boat, u = 0 Acceleration, $\mathrm{a}=3.0 \mathrm{~m} \mathrm{~s}^{-2}$ Time, $\mathrm{t}=8 \mathrm{~s}$ Distance covered, $\mathrm{s}=$ ? Using the relation $\mathrm{s}=\mathrm{ut}+\frac{1}{2} \mathrm{at}^{2}$ we have, $\mathrm{s}=0 \times 8+\frac{1}{2} \t...
Read More →How are the area of study-evolution
[question] Question. How are the area of study-evolution and classification interlinked? [/question] [solution] solution: Classification is the arrangement of organisms into groups and subgroups on the basis of their similarities and dissimilarities.The more characteristics two species will have in common, the more closely they are related. The more closely they are related, the more recently they will have had a common ancestor. So, it can be said that, classification of species is infact a ref...
Read More →State any two differences between the local government before and after the constitutional amendment in 1992.
[question] Question. State any two differences between the local government before and after the constitutional amendment in 1992. [/question] [solution] Solution: [/solution]...
Read More →What is the main difference between a federal form of government and a unitary one? Explain with an example.
[question] Question. What is the main difference between a federal form of government and a unitary one? Explain with an example. [/question] [solution] Solution: In a federal form of government, the central government shares its powers with the various constituent units of the country. For example, in India, power is divided between the government at the Centre and the various State governments. In a unitary form of government, all the power is exercised by only one government. For example, in ...
Read More →Abdul while driving to school computes the average speed for his trip to be 20 km h–1.
[question] Question. Abdul while driving to school computes the average speed for his trip to be 20 km h–1. On his return trip along the same route, there is less traffic and the average speed is 40 km h–1. What is the average speed for Abdul's trip ? [/question] [solution] Solution: Let one way distance for his trip be S. Let $t_{1}$ be the time for his trip from home to school and $t_{2}$ be the time for his return trip. Then $\mathrm{t}_{1}=\frac{\mathrm{S}}{\mathrm{v}_{1}}=\frac{\mathrm{S}}{...
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