10 YEARS- CHEMISTRY- BOARD QUESTION PAPERS WITH SOLUTION -STD 12- CBSE

Dear Students,

It is October month. All CBSE students must be looking forward to board exams , march 2016.

Its high time, when we start feeling a peculiar kind of fear. Handling the whole syllabus and preparing for board exams. Science students find it quite difficult to handle their majors -Chemistry, Physics, Maths/Biology !

Here are board papers for your help. Board question papers of last 10 years with solution. Bingo!
grab it for free.


Click the below link


10 YEARS BOARD Q PAPERS WITH SOLUTION- CHEMISTRY -CLASS 12- CBSE

NOBLE PRIZE IN CHEMISTRY 2015

Press Release

7 October 2015
The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Chemistry for 2015 to
Tomas Lindahl
Francis Crick Institute and Clare Hall Laboratory, Hertfordshire, UK
Paul Modrich
Howard Hughes Medical Institute and Duke University School of Medicine, Durham, NC, USA
and
Aziz Sancar
University of North Carolina, Chapel Hill, NC, USA
“for mechanistic studies of DNA repair"

The cells’ toolbox for DNA repair

The Nobel Prize in Chemistry 2015 is awarded to Tomas Lindahl, Paul Modrich and Aziz Sancar for having mapped, at a molecular level, how cells repair damaged DNA and safeguard the genetic information. Their work has provided fundamental knowledge of how a living cell functions and is, for instance, used for the development of new cancer treatments.

Each day our DNA is damaged by UV radiation, free radicals and other carcinogenic substances, but even without such external attacks, a DNA molecule is inherently unstable. Thousands of spontaneous changes to a cell’s genome occur on a daily basis. Furthermore, defects can also arise when DNA is copied during cell division, a process that occurs several million times every day in the human body.
The reason our genetic material does not disintegrate into complete chemical chaos is that a host of molecular systems continuously monitor and repair DNA. The Nobel Prize in Chemistry 2015 awards three pioneering scientists who have mapped how several of these repair systems function at a detailed molecular level.
In the early 1970s, scientists believed that DNA was an extremely stable molecule, but Tomas Lindahl demonstrated that DNA decays at a rate that ought to have made the development of life on Earth impossible. This insight led him to discover a molecular machinery, base excision repair, which constantly counteracts the collapse of our DNA.
Aziz Sancar has mapped nucleotide excision repair, the mechanism that cells use to repair UV damage to DNA. People born with defects in this repair system will develop skin cancer if they are exposed to sunlight. The cell also utilises nucleotide excision repair to correct defects caused by mutagenic substances, among other things.
Paul Modrich has demonstrated how the cell corrects errors that occur when DNA is replicated during cell division. This mechanism, mismatch repair, reduces the error frequency during DNA replication by about a thousandfold. Congenital defects in mismatch repair are known, for example, to cause a hereditary variant of colon cancer.
The Nobel Laureates in Chemistry 2015 have provided fundamental insights into how cells function, knowledge that can be used, for instance, in the development of new cancer treatments.
Tomas Lindahl, Swedish citizen. Born 1938 in Stockholm, Sweden. Ph.D. 1967 from Karolinska Institutet, Stockholm, Sweden. Professor of Medical and Physiological Chemistry at University of Gothenburg 1978–82. Emeritus group leader at Francis Crick Institute and Emeritus director of Cancer Research UK at Clare Hall Laboratory, Hertfordshire, UK.
http://crick.ac.uk/research/a-z-researchers/emeritus-scientists/tomas-lindahl/

Paul Modrich, U.S. citizen. Born 1946. Ph.D. 1973 from Stanford University, Stanford, CA, USA. Investigator at Howard Hughes Medical Institute and James B. Duke Professor of Biochemistry at Duke University School of Medicine, Durham, NC, USA.
http://www.biochem.duke.edu/paul-l-modrich-primary
Aziz Sancar, U.S. and Turkish citizen. Born 1946 in Savur, Turkey. Ph.D. 1977 from University of Texas, Dallas, TX, USA. Sarah Graham Kenan Professor of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
http://www.med.unc.edu/biochem/people/faculty/primary/asancar

Prize amount: 8 million Swedish krona, to be shared equally between the laureates.

The Royal Swedish Academy of Sciences, founded in 1739, is an independent organisation whose overall objective is to promote the sciences and strengthen their influence in society. The Academy takes special responsibility for the natural sciences and mathematics, but endeavours to promote the exchange of ideas between various disciplines.

Article taken from: http://www.nobelprize.org

Balancing 100 Chemical equations worksheet (With answers)

A chemical equation is the representation of a chemical reaction with the help of symbols.

Balancing chemical equations is an essential part of all chemical equations. It must be in line with 'law of conservation of mass.

There are all types of chemical equations i.e. combination, decomposition, redox etc. and all types of reactions need to be in balanced form.

Sometimes equations are written in their ionic form. In that case it must be balance in terms of charge also.

Here is available more than 300 skeletal equations to balance. Yes, answers are also provided. You just need to try out and check.

To procure all worksheets you need to visit

http://www.chemheaven.com/std-10.html 

Straight From the Horse's Mouth- Vidyagyan 1

A letter by Abraham Lincoln to his son's Teacher

Every father wants his child to get the best education so that the child may

one day grow up to be a successful person.

But them, everybody has his own perception of success.

In this letter to his son’s teacher, Abraham Lincoln requests him to inculcate

in his boy the qualities that he feels would be the best.

Read the letter and decide if you agree with Lincoln?

Dear Teacher,

HE WILL have to learn,

 I know, that all men are not just, all men are not true.

But teach him also that for every scoundrel there is a hero;

 that for every selfish politician, there is a dedicated leader.

Teach him that for every enemy there is a friend.

It will take time, I know; but teach him, if you can, that a dollar earned is of far more value than five pound. Teach him to learn to lose and also to enjoy winning.

Steer him away from envy’ if you can, teach him the secret of quiet laughter.

Let him learn early that the bullies are the easiest to lick.

Teach him, if you can, the wonder of books. But also give him quiet time to ponder the eternal mystery of birds in the sky,       bees in the sun,       and flowers on a green hillside.

In school, teach him it is far more honorable to fall than to cheat.

Teach him to have faith in his own ideas, even if everyone tells him they are wrong.

Teach him to be gentle with the gentle, and tough with the tough.

Try to give my son the strength not to follow the crowd when everyone is getting on the

bandwagon.

Teach him to listen to all men; but teach him also to filter all that he hears on a screen of

truth, and take only the good that comes through.

Teach him, if you can, how to laugh when he is sad. Teach him there is no shame in tears.

Teach him to scoff  at cynics and to beware of too much sweetness.

Teach him to sell his brawn and brain to the highest bidders, but never to put a price tag on his heart and soul.

Teach him to close his ears to a howling mob and to stand and fight if he thinks he is right.

Treat him gently, but do not cuddle him, because only the test of fire makes fine steel.

Let him have the courage to be impatient; let him have the patience to be brave.

 Teach him always to have sublime faith in himself, because then he will always have sublime faith in mankind.

This is a big order, but see what you can do. He is such a fine little fellow, my son!

A famous speech by A.P.J. Abdul Kalam

MY VISION FOR INDIA- A speech by A.P.J. Abdul Kalam

On national days such as the Republic Day and the Independence Day, you must have

heard the speeches made by our leaders. These speeches inform us about the progress of

the nation. They also tell us about some new initiatives which the government plans to take

for the continuous development of the nation. Do you feel inspired and enthusiastic when

you hear such speeches? Do they make you feel that you too should contribute a bit and

make India one of the best nations in the world?

Let us listen the speech delivered by our former President, Dr. A.P.J. Abdul Kalam and

know what his vision for India was. [Speech recited by Akash Chaudhary of Vidyagyan school]

I have three visions for India.

In 3000 years of our history people from all over the world have come and invaded us, captured our lands, conquered our minds.

From Alexander onwards the Greeks, the Turks, the Moguls, the Portuguese, the British, the French, the Dutch, all of them came and looted us, took over what was ours.

Yet we have not done this to any other nation.

We have not conquered anyone. We have not grabbed their land, their culture and their history and tried to enforce our way of life on them. Why?

Because we respect the freedom of others.

 That is why my FIRST VISION is that of FREEDOM.

I believe that India got its first vision of this in 1857, when we started the war of Independence. It is this freedom that we must protect and nurture and build on. If we are not free, no one will respect us.

We have 10 percent growth rate in most areas.

Our poverty levels are falling.

 Our achievements are being globally recognised today.

Yet we lack the self-confidence to see ourselves as a developed nation, self-reliant and self-assured.

Isn’t this incorrect?

MY SECOND VISION for India is DEVELOPMENT.

 For fifty years we have been a developing nation.

 It is time we see ourselves as a developed nation.

 We are among top five nations in the world in terms of GDP.

I have a THIRD VISION.

India must stand up to the world. Because I believe that unless India stands up to the world, no one will respect us.

Only strength respects strength.

We must be strong not only as a military power but also as an economic power.

Both must go hand-in-hand.

My good fortune was to have worked with three great minds.

 Dr.Vikram Sarabhai, of the Dept. of Space,

 Professor Satish Dhawan, who succeeded him

 and Dr. Brahm Prakash, father of nuclear material.

I was lucky to have worked with all three of them closely and consider this the great opportunity of my life.

I was in Hyderabad giving this lecture, when a 14 year-old girl asked me for my autograph.

I asked her what her goal in life is.

She replied: I want to live in a developed India.

 For her, you and I will have to build this developed India. You must proclaim India is not an underdeveloped nation; it is a highly developed nation.

You say that our government is inefficient.

 You say that our laws are too old.

You say that the municipality does not pick up the garbage.

You say that the phones don’t work,

The railways are a joke,

The airline is the worst in the world,and

Mails never reach their destination.

You say that our country has been fed to the dogs and is the absolute pits.

You say, say and say.

What do you do about it?

Dear Indians, I am echoing J.F.Kennedy’s words to his fellow Americans to relate to

Indians …….

“ASK WHAT WE CAN DO FOR INDIA AND DO WHAT HAS TO BE DONE TO MAKE INDIA WHAT AMERICA AND OTHER WESTERN COUNTRIES ARE TODAY.”

JAI HIND



You can get this speech  in video form here 

Worksheet on Radicals (Cations and Anions)

Worksheet  on radicals [Cations and Anions]                           Name……………………………………………..Class/Sec……………………….…Date………………….

Cations/ Basic radicals

Monovalent cations	Bivalent cations
Monoatomic Cations    H+         hydrogen Li+          lithium Na+        sodium K+           potassium Rb+        rubidium Cs+         cesium Ag+         silver Cu+       copper(I) or cuprous Hg22+     mercury(I)  or  mercurous Au+       gold(I) or aurous Polyatomic Cations NH4+     ammonium H3O+     hydronium	Mg2+     magnesium Ca2+      calcium Sr2+          strontium Ba2+         barium Zn2+        zinc Cd2+      cadmium Be2+        beryllium ion Cu2+       copper(II)  or cupric Fe2+         iron(II)  or ferrous Sn2+        tin(II)  or  stannous Mn2+      manganese(II)  or manganous Hg2+       mercury(II)    or  mercuric Pb2+         lead(II)  or   plumbous Cr2+        chromium(II)  or chromous
Trivalent cations	Tetravalent cations
Al3+       aluminum Fe3+       iron(III)   or   ferric Cr3+       chromium(III)  or chromic Mn3+     manganese(III)  or manganic Co3+       cobalt(III)  or cobaltic Au3+      gold(III)  or auric	Sn4+       tin(IV)  or  stannic Pb4+        lead(IV)  or plumbic

Anions   /Acidic radicals

Monovalent anions	Bivalent anions
H-  hydride      F- fluoride     Cl- chloride    Br- bromide  I- iodide OH-          hydroxide CN-          cyanide O22-         peroxide NO2-      nitrite                        NO3-  nitrate ClO2-     chlorite ClO3-    chlorate                     IO3¯ iodate          BrO3¯ bromate CH3COO- or C2H3O2-   acetate MnO4-  permanganate CHO2-   formate or HCOO-1 HCO3-  hydrogen carbonate or bicarbonate HSO3-  hydrogen sulphite  or bisulphite HSO4-   hydrogen sulphate or bisulphate H2PO4-  dihydrogen phosphate	O2-              oxide S2-           sulphide CO3 2-       carbonate C2O42-       oxalate SO32-       sulphite SO42-       sulphate CrO42-      chromate Cr2O72-   dichromate HPO4 2-    hydrogen phosphate
Triivalent anions	Tetravalent anions
N3-               nitride P3-                 phosphide PO33-          phosphite                 PO43-          phosphate	C4- (C22-)     carbide [Fe(CN)6]-4

Metals with more than one ion

Element	Ion	Stock system	Classical (ous, ic) System
Chromium	Cr2+ Cr3+	chromium(II) chromium(III)	chromous chromic
Cobalt	Co2+ Co3+	cobalt(II) cobalt(III)	cobaltous cobaltic
Copper	Cu+ Cu2+	copper(I) copper(II)	cuprous cupric
Iron	Fe2+ Fe3+	iron(II) iron(III)	ferrous ferric
Lead	Pb2+ Pb4+	+ lead(II) lead(IV)	plumbous plumbic
Manganese	Mn+2 Mn4+ Mn3+ Mn5+ Mn6+ Mn7+	manganese(II) manganese(IV) manganese(III) manganese(IV) manganese(VI) manganese(VII)	Manganous manganic -        [Not possible] -       [Not possible] -       [Not possible] -       [Not possible]
Mercury	Hg22+ Hg2+	mercury(I) mercury(II)	Mercurous mercuric
Tin	Sn2+ Sn4+	tin(II) tin(IV)	Stannous stannic
Gold	Au+ Au3+	gold(I) gold(III)	Aurous  auric

·         Prefixes Used to Indicate Number in a Name Involving Two Non-Metals

mono– 1                      hexa– 6

di–       2                      hepta– 7

tri–      3                      octa– 8

tetra– 4                      nona– 9

penta–  5                     deca– 10

·         These prefixes are used in naming binary compounds involving two non–metals. Example include P₂O₅, Cl₂O, NO, N₂O, NO₂, N₂O₅, PCl₃, PCl₅, SO₂, SO₃, SiO₂.

·         Sometimes metal ions are involved in a Greek prefix name, but these are less common. Examples include UF6, SbCl3,

SbCl₅, OsO₄, BiCl₃.

·         CO is carbon monoxide, NOT carbon monooxide. As₄O₆ is tetrarsenic hexoxide, NOTtetraarsenic hexaoxide.

·         Acid Names – add the word acid to each name when saying or writing.

·                                                              Name when a pure compound      Name when dissolved in water      

                                                                                   

HF       hydrofluoric acid                   hydrogen fluoride                             HNO₃ nitric acid

HCl     hydrochloric acid                 hydrogen chloride                            HNO₂ nitrous acid

HBr     hydrobromic acid                 hydrogen bromide                            H₂SO₄ sulfuric acid

HI        hydroiodic acid                      hydrogen iodide                     H₂SO₃ sulfurous acid

HCN   hydrocyanic acid                   hydrogen cyanide                 H₃PO₄ phosphoric acid

H₂S      hydrosulfuic acid                   hydrogen sulphide                H₂CO₃ carbonic acid

       

          Acetic acid  CH₃COOH)

What are the Latin Names of  Elements?

Scientists have adopted certain conventions regarding the chemical symbols for various elements. The symbol is the short form or abbreviated name of the element. Each element has a chemical symbol that is unique to it. An atom of an element is denoted by this symbol. For example, the symbol for Carbon is C.

Many elements have their symbol derived from either the first letter [e.g., H for Hydrogen] or the first two letters [e.g., He for Helium] of their names. A few elements have symbols derived from their Latin names as given in the table below.

Element	Symbol	Latin Name
Antimony	Sb	Stibium
Copper	Cu	Cuprum
Gold	Au	Aurum
Iron	Fe	Ferrum
Lead	Pb	Plumbum
Mercury	Hg	Hydragyrum
Potassium	K	Kalium
Silver	Ag	Argentum
Sodium	Na	Natrium
Tin	Sn	Stannum
Tungsten	W	Wolfram[German name]

 

Ionic Compound Formula Writing Worksheet

QUESTION-1

Write chemical formulas for the compounds in each box.  The names are found by finding the intersection between the cations and anions.  Example:  The first box is the intersection between the “zinc” cation and the “chloride” anion, so you should write “ZnCl₂”, as shown.

	zinc	iron (II)	iron (III)	Calcium	silver	lead (IV)
chloride	ZnCl2
acetate
nitrate
oxide
nitride
sulphate

QUESTION-2

Write the formulas for the following compounds:

1)         copper (II) chloride _____________________2)       lithium acetate _______________________

3)         Ammonium nitrate______________                4)  manganese (IV) nitride _________________

5)         Magnesium oxide _____________                  6)  sodium sulphate ________________________

7)         aluminum bromide _______________            8)  potassium permanganate __________________

9)         Potassium cyanide ________________          10)      tin (II) sulphite ______________________

11)       Barium fluoride _________________          12)        ammonium nitrite ___________________

Question 3

Give the name  or formula of the following ionic compounds:

1)         Na2CO3 ­­­­­____________________ 2)         NaOH ______________________ 3)         MgBr2  ______________________ 4)         KCl  ________________________ 5)         FeCl2 _______________________ 6)         FeCl3 _______________________ 7)         Zn(OH)2  _____________________ 8)         Be2SO4  _____________________ 9)         CrF2   ________________________ 10)       Al2S3  _______________________ 11)       PbO  ________________________ 12)       Li3PO4  ______________________ 13)       CaS   _________________________ 14)       Ca3N2   ______________________

15)       Mg3P2   ______________________ 16)       Mg(NO2)3   ____________________ 17)       Ag2SO3  ______________________ 18)       NH4OH  ______________________ 19)       Al(CN)3 ____________________ 20)       Ca(CH3COO)2   ________________ 21)       sodium phosphide _____________ 22)       magnesium nitrate _____________ 23)       lead (II) sulphite ___________ 24)       calcium phosphate _____________ 25)       ammonium sulphate _____________ 26)       silver cyanide _________________ 27)       aluminum  sulphide ____________ 28)       beryllium chloride ______________

29)       copper (I) arsenide _____________ 30)       iron (III) oxide _________________ 31)       Ferric nitride _________________ 32)       iron (II) bromide  _______________ 33)       Barium phosphate  ________ 34)       calcium oxide _________________ 35)       magnesium acetate  ____________ 36)       aluminum sulphate  ______________

37)       copper (I) carbonate ____________ 38)       barium oxide __________________ 39)       ammonium sulphite____________ 40)       silver bromide _________________