What is a good source of energy?
Good sources of energy are
(I) It should have high calorific value.
(II) It does a huge amount of work per unit mass.
(III) It should be easy to handle.
(IV) It should be easy to store and transport.
(V) It must be cheap.
(VI) It produces less amount of smoke and is eco friendly.
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?
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?
Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices.
What are the qualities of an ideal source of energy?
Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun’s energy?
(a) geothermal energy (b) wind energy
(c) nuclear energy (d) bio-mass.
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?
What is the difference between a reflex action and walking?
One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.
Which metals do not corrode easily?
What is the role of the acid in our stomach?
Give an example of a double displacement reaction other than the one given in activity 1.10.
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?
The magnetic field in a given region is uniform. Draw a diagram to represent it.
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?
The human eye forms the image of an object at its
(a) cornea. (b) iris. (c) pupil. (d) retina.
How many structural isomers can you draw for pentane?