Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Two exhaustible energy sources are as follows: coal and wood
(a) Coal: It is formed from the remains of dead plants and animals that have been buried under the earth’s crust for millions of years. It takes millions of years to produce coal. Industrialization has increased the demand of coal. However, coal cannot replenish within a short period of time. it is a nonrenewable or exhaustible source of energy.
(b) Wood: It is obtained from forests. Deforestation at a faster rate has caused a reduction in the number of forests on our planet. It takes hundreds of years to grow a forest. If deforestation is continued at this rate, then there would be no wood left on the Earth. Hence, wood is an exhaustible source of energy.
Can any source of energy be pollution-free? Why or why not?
What are the limitations of the energy that can be obtained from the oceans?
If you could use any source of energy for heating your food, which one would you use and why?
On what basis would you classify energy sources as
(a) renewable and non-renewable?
(b) exhaustible and inexhaustible?
Are the options given in (a) and (b) the same?
What is a good source of energy?
Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Which of the following is not an example of a bio-mass energy source?
(a) wood (b) gobar-gas
(c) nuclear energy (d) coal
What are the disadvantages of fossil fuels?
Name two energy sources that you would consider to be renewable. Give reasons for your choices.
How has the traditional use of wind and water energy been modified for our convenience?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the difference between a reflex action and walking?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
Name the type of mirror used in the following situations.
(a) Headlights of a car.
(b) Side/rear-view mirror of a vehicle.
(c) Solar furnace.
Support your answer with reason.
Would you be able to check if water is hard by using a detergent?
How does our body respond when adrenaline is secreted into the blood?
What are outside raw materials used for by an organism?
Redraw the circuit of Question 1, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the 12 Ω resistor. What would be the readings in the ammeter and the voltmeter?
In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better’ body design? Why or why not?
Why does distilled water not conduct electricity, whereas rain water does?
Give any two ways in which biodegradable substances would affect the environment.
What is a balanced chemical equation? Why should chemical equations be balanced?
Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.