(ii) Science questions HELP !!!?

Question

Is the number of elements likely to increase or decrease in the future? why so?

What is the most abundant element in our Earth's crust?

Why is carbon used as/for/in
(i) formation of living tissues?
(ii) as a fuel
(iii) pencil leads

Why is hydrogen used for:
(i) making margarine
(ii) as rocket fuel
(iii) for filling weather balloons

Why is sulphur used
(i) for making insecticides
(ii) for making medicinal drugs
(iii) for hardening rubber used in making car tyres

Why is oxygen used for
(i) Respiration -why is it necessary? To which organ?
(ii) for combustion
(iii) in oxy-acetylene flames for weilding

Why is Nitrogen used
(i) for the formation of plant and animal proteins
(ii) in the manufacture of fertilisers
(iii) in the liquid agent as a cooling agent

Is a compound formed when iron rusts? If so, what is the compound formed and what are the reactants that form the compound?

Answer 1

wow.. thats hell lot of a work.. never mind.. i have time for everyone.. ill give it my best shot

1)i) carbon is the most common consitituent element i the universe
ii) you mean methane CH3 etc. cuz it combusts well
iii) it is lighter and is found in many forms. look at nature.. diamond is carbon but thus it is so beautiful. the carbon that rust our metal bodies is equally ugly..

Answer 2

As we continue to find new materials, I think it's gonna increase.
1. The most abundant element in the earth's crust is oxygen, making up 46.6% of the earth's mass.
2. for the 1 nd 3 option.
3. As a rocket fuel.
4. For hardening of natural rubber. nd is used in rest of the two, too.
5. all three, nd oxygen is used to oxydize the food which u eat. It breaks it down to release energy
6. in the last 2 options

When iron rusts it foms Fe2O3, the reactants r iron, air nd water.

Answer 3

I will answer the last.

Is a compound formed when iron rusts? If so, what is the compound formed and what are the reactants that form the compound?

Yes. It forms iron oxide. Iron and oxygen from the air.