hello

[Mark]

Dear Sir/Madam
Iam Chris studing in Our Own Indian School Dubai. I have some doubts in chemistry
1) Reactive of elements in the Mordern Perodic Table (Arrangments)
2) Electro positive and electronegative of elements .In the perodic table (arrangment)
3) Important parts in Carbon and its Compounds
4) Merits of covalent bonds and demerits of ionic compounds
5) Difference b/w ethane and ethyne
6) Merits of Mendaleevs periodic table
7) Demrits of Mendaleevs periodic table which was fulfilled by the mordern table
8) If diluted acids are less reactive/crossive the how is acid rain are affecting the ecosystem
I hope you would answer my to my mail
Thanking you
--
Chris Mathews

[Binsi]

1.carbon and compounds all are important......mainly concntrate on reasoning type questions.

2.diff b/w ethane and ethyne is in ethane there is only single bond but ethyne triple bond

3.merits of mendeleeves periodic table was that he was the only one to give a proper arrangement of all elements and formulated the periodic law which was applicable to all elements, also noble gases which were dicovered later could be placed in another row without disturbing original arrangement,and he predicted existence of other elements like eka alluminium etc...

4.demerits are that he could not give proper position to hydrogen,couldnt give position to isotopes, elements with higher atomic mass was placed before the ones with lower atomic mass in some cases.

5.all plants and animals can survive only a specific ph range when ph gets too acidic survival becomes difficult. it shoud be understood that any change in the natural balance can cause adverse effects.

these r just my explanations......it would be gud if u refer your text book.....all these points are very well mentioned.

also try out http://www.cbsetutor.com for explanations

[teena chandran]

5. it also affect aquotic balance