Name the petroleum product used
Question: Name the petroleum product used as fuel for stoves, lamps and jet aircrafts. Solution: Kerosene is a petroleum product which is used as fuel for stoves, lamps and jet aircrafts....
Read More →The sides of an equilateral triangle are increasing at the rate of 2 cm/sec.
Question: The sides of an equilateral triangle are increasing at the rate of 2 cm/sec. The rate at which the area increases, when the side is 10 cm, is _____________. Solution: Letxbe the side andAbe the area of an equilateral triangle at any timet. It is given that $\frac{d x}{d t}=2 \mathrm{~cm} / \mathrm{sec}$ Area of the equilateral triangle, $A=\frac{\sqrt{3}}{4}(\text { Side })^{2}=\frac{\sqrt{3}}{4} x^{2}$ $A=\frac{\sqrt{3}}{4} x^{2}$ Differentiating both sides with respect tot, we get $\...
Read More →What does CNG stand for and
Question: What does CNG stand for and why is it considered to be a better fuel than petrol? Solution: CNG stands for Compressed Natural Gas. It is considered to be a better fuel because it bums with a smokeless flame and causes no air pollution. It also does not produce any poisonous gases on burning....
Read More →The sides of an equilateral triangle are increasing at the rate of 2 cm/sec.
Question: The sides of an equilateral triangle are increasing at the rate of 2 cm/sec. The rate at which the area increases, when the side is 10 cm, is _____________. Solution: Letxbe the side andAbe the area of an equilateral triangle at any timet. It is given that $\frac{d x}{d t}=2 \mathrm{~cm} / \mathrm{sec}$ Area of the equilateral triangle, $A=\frac{\sqrt{3}}{4}(\text { Side })^{2}=\frac{\sqrt{3}}{4} x^{2}$ $A=\frac{\sqrt{3}}{4} x^{2}$ Differentiating both sides with respect tot, we get $\...
Read More →You are provided with a mixture
Question: You are provided with a mixture of petroleum and water. Can you suggest a method to separate the two? Solution: Decantation can be used to separate a mixture of petroleum and water. The mixture is allowed to stand. Petroleum is lighter than water, so it floats over water, Carefully, lighter layer of petroleum can be poured and separated without disturbing the heavier layer of water....
Read More →Choose the correct statement from the following.
Question: Choose the correct statement from the following. (a) It is difficult to transport natural gas through pipes (b) The disadvantage of natural gas is that it cannot be used directly for burning in homes (c) Natural gas is stored under high pressure as compressed natural gas (d) Natural gas cannot be used for power generation Solution: (c) Natural gas is stored under high pressure as compressed natural gas. Note:It is easy to transport natural gas through pipes and it can be used directly ...
Read More →Petroleum was formed from organisms
Question: Petroleum was formed from organisms (a) living on the land (b) living on the plants (c) living in the sea (d) living on the rocks Solution: (c) Petroleum was formed by the decomposition of the remains of tiny plants and animals buried under the sea millions of years ago....
Read More →Which of the following is not a constituent
Question: Which of the following is not a constituent of petroleum? (a) Paraffin wax (b) Lubricating oil (c) Petrol (d) Coke Solution: (d) Coke is not a constituent of petroleum. Coke is prepared by heating coal in the absence of air....
Read More →Naphthalene balls are obtained
Question: Naphthalene balls are obtained from coal tar and are used as (a) mosquito repellant (b) honeybee repellant (c) moth repellant (d) snake repellant Solution: (c) Naphthalene balls are used to repel moths and other insects (in stored clothes, etc)....
Read More →Which substance is formed
Question: Which substance is formed by the carbonisation of dead vegetation? (a) Coal (b) Coke (c) Coal gas (d) Coal tar Solution: (a) Coal is formed by the carbonisation Qf dead vegetation....
Read More →Find the sum of the series whose nth term is given by:
Question: Find the sum of the series whose nth term is given by: $\left(2 n^{2}-3 n+5\right)$ Solution: It is given in the question that the $n^{\text {th }}$ term of the series, $a_{n}=2 n^{2}-3 n+5$ Now, we need to find the sum of this series, Sn $\mathrm{S}_{\mathrm{n}}=\sum_{\mathrm{n}=1}^{\mathrm{n}} \mathrm{a}_{\mathrm{n}}$ $\mathrm{S}_{\mathrm{n}}=\sum_{\mathrm{n}=1}^{\mathrm{n}}\left(2 \mathrm{n}^{2}-3 \mathrm{n}+5\right)$ $=\sum_{\mathrm{n}=1}^{\mathrm{n}}\left(2 \mathrm{n}^{2}\right)-\...
Read More →Coal is formed from the remains of
Question: Coal is formed from the remains of (a) vegetation only (b) animals only (c) both vegetation and animals (d) neither vegetation nor animals Solution: (a) Coal is formed by the decomposition of large land plants and trees buried under the earth about 300 million years ago....
Read More →Fossil fuels are obtained from
Question: Fossil fuels are obtained from (a) remains of non-living materials (b) dead remains of birds only (c) dead remains of insects only (d) dead remains of living organisms Solution: (d) Fossil fuels are obtained from the remains of living organisms (plants and animals) buried under the earth millions of years ago. Note Coal, petroleum and natural gas are fossil fuels....
Read More →Exhaustible natural resources are
Question: Exhaustible natural resources are (a) unlimited in quantity (b) not dependent on nature (c) limited in quantity (d) not exhausted by human activities Solution: (c) Exhaustible natural resources are present in a limited quantity in nature and can be exhausted by human activities. Note Coal, petroleum, natural gas, minerals, forests and wildlife, etc are exhaustible natural resources....
Read More →The angle θ,
Question: The angle $\theta, 0\theta\frac{\pi}{2}$, which increases twice as fast as its sine, is ______________ Solution: Let angleincrease twice as fast as its sine. It is given that, $\frac{d \theta}{d t}=2 \frac{d}{d t}(\sin \theta)$ $\Rightarrow \frac{d \theta}{d t}=2 \cos \theta \frac{d \theta}{d t}$ $\Rightarrow 2 \cos \theta=1$ $\Rightarrow \cos \theta=\frac{1}{2}=\cos \frac{\pi}{3}$ $\Rightarrow \theta=\frac{\pi}{3}$ $\left(0\theta\frac{\pi}{2}\right)$ Thus, the angle $\theta$ is $\frac...
Read More →Coal is processed in industries to get some
Question: Coal is processed in industries to get some useful products. Which of the following is not obtained from coal? (a) Coke (b) Coal tar (c) Coal gas (d) CNG Solution: (d) CNG (Compressed Natural Gas) is not obtained from coal. Note :Natural gas is formed under the earth by the decomposition of vegetable matter lying under water....
Read More →Which of the following is a pair
Question: Which of the following is a pair of exhaustible natural resources? (a) Coal and soil (b) Air and sunlight (c) Water and petroleum (d) Wildlife and minerals Solution: (d) Wildlife and minerals are exhaustible natural resources because these resources are present in a limited quantity in nature and can be exhausted by human activities....
Read More →Air is a natural resource and cannot be
Question: Air is a natural resource and cannot be exhausted by human activities. It is known as inexhaustible natural resource. Which of the following is another inexhaustible natural resource? (a) Coal (b) Petroleum (c) Sunlight (d) Minerals Solution: (c) Sunlight, air and water are inexhaustible natural resources that means which cannot be exhausted by human activities....
Read More →The angle θ,
Question: The angle $\theta, 0\theta\frac{\pi}{2}$, which increases twice as fast as its sine, is ______________ Solution: Let angleincrease twice as fast as its sine. It is given that, $\frac{d \theta}{d t}=2 \frac{d}{d t}(\sin \theta)$ $\Rightarrow \frac{d \theta}{d t}=2 \cos \theta \frac{d \theta}{d t}$ $\Rightarrow 2 \cos \theta=1$ $\Rightarrow \cos \theta=\frac{1}{2}=\cos \frac{\pi}{3}$ $\Rightarrow \theta=\frac{\pi}{3}$ $\left(0\theta\frac{\pi}{2}\right)$ Thus, the angle $\theta$ is $\frac...
Read More →Various materials which are obtained
Question: Various materials which are obtained from nature are called natural resources. Which of the following is not a natural resource? (a) Minerals (b) Water (c) Soil (d) Plastic Solution: (d) Minerals, water and soil are natural resources but plastic is a man-made material. So, plastic is not a natural resource....
Read More →The rate of change of volume of a sphere with respect to its surface area,
Question: The rate of change of volume of a sphere with respect to its surface area, when the radius is 2 cm, is _________________. Solution: Letrbe the radius of the sphere at any timet. Volume of the sphere, $V=\frac{4}{3} \pi r^{3}$ $V=\frac{4}{3} \pi r^{3}$ Differentiating both sides with respect to $r$, we get $\frac{d V}{d r}=\frac{4}{3} \pi \times \frac{d}{d r} r^{3}$ $\Rightarrow \frac{d V}{d r}=\frac{4}{3} \pi \times 3 r^{2}$ $\Rightarrow \frac{d V}{d r}=4 \pi r^{2}$ Surface area of the...
Read More →The rate of change of volume of a sphere with respect to its surface area,
Question: The rate of change of volume of a sphere with respect to its surface area, when the radius is 2 cm, is _________________. Solution: Letrbe the radius of the sphere at any timet. Volume of the sphere, $V=\frac{4}{3} \pi r^{3}$ $V=\frac{4}{3} \pi r^{3}$ Differentiating both sides with respect to $r$, we get $\frac{d V}{d r}=\frac{4}{3} \pi \times \frac{d}{d r} r^{3}$ $\Rightarrow \frac{d V}{d r}=\frac{4}{3} \pi \times 3 r^{2}$ $\Rightarrow \frac{d V}{d r}=4 \pi r^{2}$ Surface area of the...
Read More →Find the sum of the series whose nth term is given by
Question: Find the sum of the series whose nth term is given by $\left(3 n^{2}-3 n+2\right)$ Solution: It is given in the question that the $\mathrm{n}^{\text {th }}$ term of the series, $a_{n}=3 n^{2}-3 n+2$ Now, we need to find the sum of this series, $\mathrm{Sn}$. $\mathrm{S}_{\mathrm{n}}=\sum_{\mathrm{n}=1}^{\mathrm{n}} \mathrm{a}_{\mathrm{n}}$ $S_{n}=\sum_{n=1}^{n}\left(3 n^{2}-3 n+2\right)$ $=\sum_{n=1}^{n}\left(3 n^{2}\right)-\sum_{n=1}^{n}(3 n)+\sum_{n=1}^{n}(2)$ $=3 \sum_{n=1}^{n}\left...
Read More →Fill in the blanks to complete the following paragraph.
Question: Fill in the blanks to complete the following paragraph.The name of the product formed in the reaction of sulphur and is sulphur dioxide gas. When sulphur dioxide is dissolved in sulphurous acid is formed. The sulphurous acid turns litmus paper toGenerally, oxides of are acidic in nature. After completing the paragraph, write two questions which you can raise on the basis of this information. Solution: Oxygen, water, blue, red, non-metals. Questions may be : Which gas is formed when sul...
Read More →State whether the following statement are True/False.
Question: State whether the following statement are True/False. The property of metals by virtue of which they can be drawn into wires is called ductility. Metals are good conductors of electricity but poor conductor of heat. Articles made up of metals produce ringing sound when struck hard. Oxides of non-metals and metals are acidic in nature. A less reactive metal displaces a more reactive metal from its salt solution in water. Solution: True False, metals are good conductors of heat and elect...
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