Hydrogen has been used as a rocket fuel. Would you consider it a cleaner fuel than CNG? Why or why not?
Hydrogen Gas is cleaner to CNG. hydrogen is waste-free. The fusion of hydrogen does not produce any waste. Whereas CNG contains hydrocarbons. Therefore, it has carbon contents. Carbon is a form of pollutant present in CNG. Hence, hydrogen is cleaner than CNG.
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?
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?
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.
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?
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.
Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
What are the components of the transport system in human beings? What are the functions of these components?