Very Short Answer Questions - 1 Mark

Que 1. What type of reactions occur inside the Sun which produces solar energy?

Ans. The nuclear fusion reactions taking place inside the Sun produce solar energy.

Que 2. Which of the following are renewable and which are non-renewable sources of energy?

             Coal, wind, tides, Sun, petrol, biomass, CNG, hydro energy.

Ans. Re newable sources: wind, tides, Sun, biomass, hydro energy

         Non-renewable sources: coal, petrol, CNG 

Que 3. Which part of Sun's energy is responsible for drying clothes and exposure to which part could be a health hazard? 

Ans. Infra-red (IR) radiations are responsible for drying clothes and ultraviolet (UV) radiations could be a health hazard. 

Que 4. What type of energy is possessed by wind?

Ans. Kinetic energy

Que 5. Though a hot iron emits radiations, yet it is not visible in the dark, why? 

Ans. Hot iron emits infrared rays. These rays are invisible to the eyes. 

Que 6. What is bagasse? 

Ans. Bagasse is the remaining part of the sugarcane from which juice has been extracted. 

Que 7. Define anaerobic degradation.

Ans. The decomposition which takes place in the absence of oxygen by anaerobic bacteria is called anaerobic degradation.

Que 8. Name the main constituent of biogas.

Ans. The main constituent of biogas is methane (75%).

Que 9. What is the minimum wind velocity required for obtaining useful energy with a windmill?

Ans. Minimum velocity required for obtaining useful energy with a windmill is about 15 km/h.

Q. 10. Name two forms of energy in which solar energy manifests itself in oceans.

Ans. (i) Tidal energy, and (ii) Ocean thermal energy. 

Que 11. Name any two materials that are used for making solar cells.

Ans. (i) Silicon, and (ii) Gallium or selenium.

Que 12. What is the range of wavelength of electromagnetic waves that constitute visible radiation? 

Ans. The range of electromagnetic waves is about 4000  which constitute visible radiation. 

Que 13. What steps would you suggest to help minimise environmental pollution caused by burning of fossil fuels? 

Ans. (i) Use of smokeless appliances                 (ii) Afforestation 

Que 14. State the two forms of energy in which energy is mainly utilised at our homes. 

Ans. (i) Heat energy, and (ii) light energy. 

Que 15. What are the different types of nuclear reactions? 

Ans. There are two types of nuclear reactions: 

(i) Nuclear fission (ii) Nuclear fusion. 

Que 16. Why does acid rain happen? 

Ans. Acid rain happens because of burning of fossil fuels which release oxides of carbon, nitrogen and sulphur in the atmosphere. 

Que 17. What energy transformation occur in a hydro power plant? 

Ans. In a hydro power plant potential energy possessed by stored water is converted into electrical energy. 

Que 18. What is a chain reaction? 

Ans. A reaction in which the particle which initiates (starts) the reaction is also produced during the reaction to carry on the reaction further and further is called a chain reaction.