question_answer

  Mention advantages and disadvantages of producing hydro electricity by construction of dams. Or Explain the difference between nuclear fusion and fission reactions with examples. Why can't energy due to fusion be used to meet our day-to-day energy needs?

Answer:

  Advantages and disadvantages of constructing dam for electricity generations are

S. No.	Advantages	Disadvantages
(i)	Hydel power is renewable source.	A lot of plants, animals and their habitat get submerged in water.
(ii)	Reservoirs help in development of fishing industry.	The downstream land becomes less fertile, sometimes barren.
(iii)	(iii) Water can be stored for irrigation and purification.	A large number of people are displaced. Construction of dam requires huge capital investment.

(5) Or The differences between nuclear fusion and fission are given below

S. No.	Nuclear fusion	Nuclear fission
(i)	Smaller nuclei fuse to form bigger nucleus.	Bigger nucleus splits to form two or more smaller nuclei.
(ii)	High temperature and pressure are required to start reaction.	The nucleus needs to be bombarded with neutron.
	(iii) Heat produced is higher than that produced in nuclear fission.
(iv)	No radioactive byproducts are released.	Radioactive byproducts are released.

(4) Nuclear fusion cannot be used to meet our daily demands because it generates tremendously large amount of heat. It also requires high temperature and pressure conditions to initiate the reaction.                                            (1)