Why are we looking at alternate sources of energy?
Non conventional sources of energy are better than Fossil fuels, which have been traditionally used by human beings as energy sources, are non-renewable sources of energy. These sources of energy are limited and cannot replenish on their own. They are being consumed at a large rate. If this rate of consumption continues, then the fossil fuels would be exhausted from the Earth. Therefore, we have to conserve the energy sources. Hence, we should look for alternate sources 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?
Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
What is a good source of energy?
What are the disadvantages of fossil fuels?
Which of the following is not an example of a bio-mass energy source?
(a) wood (b) gobar-gas
(c) nuclear energy (d) coal
Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
Name two energy sources that you would consider to be renewable. Give reasons for your choices.
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?
An electric oven of 2 kW power rating is operated in a domestic electric circuit (220 V) that has a current rating of 5 A. What result do you expect? Explain.
What is the far point and near point of the human eye with normal vision?
Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other? Name this gas.
Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?
What is the importance of DNA copying in reproduction?
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
(a) calcium
(b) carbon
(c) silicon
(d) iron.
Define 1 dioptre of power of a lens.
A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens? Draw the ray diagram.
How does phototropism occur in plants?
What are the methods used by plants to get rid of excretory products?