Question

answer both
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Answer 1

Two reasons to harness non-conventional source of energy are as follows:-

i)Coal petroleum and other conventional sources are non-renewable due to which they can end any time.

ii)To meet the future requirements as well as future generation should be able to get benefit of this resources.

iii)To meet present as well as future requirements it is necessary to use non-conventional source of energy.

2)Atomic no. = mass no. - No. of neutrons

=>35-18

=>17

Hence the element is chlorine and it belongs to 17th group of periodic table called halogens and 3rd period

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Answer 2

The first Questions answer-->

There is an urgent need to harness non convectional sources of energy as:-

1)The renewable resources are available in a limited quantity which will soon get exhausted .Non convectional sources like the wind,sun,water,ocean thermal plant,etc will renew every now and then and we can utilize them.

2)The non-convectional sources are mostly non-polluting sources of energy and they are very environmental friendly.

The second Questions answer-->

Mass number=35

Neutron=18

remember One formula

Neutron+Proton=Mass number

18+Proton=35

Proton=35-18

Proton=17

The atomic number=No of proton=17

The element is Cl (Chlorine)

ONE MORE FORMULA  NO OF PERIOD=NO OF SHELLS

Atomic configuration of Cl =2,8,7

So period number=3

Group no=17

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