Answer:
1 ans: d. all seeds has young plant, stored food and a seed coat.
2 ans: d. the right pollen is placed on their stigmas
3 ans: a. pollen grain falls on a pistil
4 ans: a. fire
5 ans: b. sexual
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A catalyst is a substance that increases the rate of a chemical reaction without itself being consumed . (ans: second choice)
H₂ = 2 g/mol
1 x 2 = 2 g of H₂
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K = 39.09 g/mol
2 x 39.09 = 78.18 g of K
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Mg = 24.3 g/mol
3 x 24.3 = 72.9 g of Mg
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He = 4 g/mol
4 x 4 = 16 g of He
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Order : K , Mg , He and H₂
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<span>the separation of air into oxygen, nitrogen, and other components?</span>
Answer : The correct answer is A. Nuclear reactors using Pu-239
B. burning coal
The sources which are not renewable are known as "non- renewable sources of energy .
Non - renewable sources are those which get expired after rapid use and can never be reproduced . These sources replenishes in very long time . Examples : Coal , petrol or fuels etc .
1) Nuclear reactors using Pu-239 : Nuclear reactors uses radioactive elements like uranium , plutonium etc , which are present in limit . after frequent use of these elements , they will vanish off , Hence we can say nuclear reactors are Non renewable source of energy .
2) Burning coal : Coal is used as one of the major source of fuel . On rapid utilization of coal they will finished from earth . It takes thousand of year for formation of coal . Hence , it is a Non -renewable source .
3) Photo-voltaic cell: These are cells which used solar energy . Solar energy is obtained from sun . Hence solar energy is renewable source of energy so is the photo voltaic cell .
4) Geothermal energy : Geothermal energy is source of energy that is extracted from earth's thermal energy . Since thermal energy of earth is present in very large amount and can be reproduced , hence it renewable source of energy .
5)Wind energy : Wind energy is source of energy that is obtained from wind. And wind is renewable source so the wine energy too .
Consequently , we can say only two of them " Nuclear reactors and burning of coal " are Non renewable force of energy .