Detection of nitrogen in organic compond | Chemistry HSEB notes XI

Sodium extract solution is prepared and 1ml of that Na extract solution is taken in a clean test-tube and added few drops of sodium hydroxide solution if sodium extract solution is not Alkaline. To this solution 1ml of freshly prepared ferrous sulphate is added. Whole solution is then heated to boiling for few minutes. The solution is then cooled under tap . To this cooled solution 8-10 drops of concentrated hydrochloric acid is added and 1 drop of ferric chlorite solution is added. After this, apperance of Prussian  blue or green precipitation of ferric ferrocynate conforms the presence of Nitrogen in given organic compound.

Reaction involved :

1.     Organic compound containing Nitrogen during sodium fusion give NaCN which is water soluble ionic salt so sodium extract solution contain NaCN.

    

          Na + C + N ----------------> NaCN

    

     2.     Excess of sodium if remained reacts with water to give NaOH.

      

          Na + H2O ------------------> NaOH + H2

     3. This sodium hydroxide solution and added NaOH reacts with ferrous sulphate to      give ferrous hydroxide which has dirty green colour.

          FeSo4 + 2NaOH ----------------> Fe(OH)2 + Na2So4 (dirty green ppt)

     4. Ferrous hydroxide then reacts with NaCN to give sodium ferrocyanide.

          Fe(OH)2 + 6NaCN ----------------> Na4[Fe(CN)6] + NaOH (sodium ferrocyanide)

5. Sodium ferrocyanide then reacts with ferric chloride solution to give ferric ferrocyanide which has prussion blue or green colour which comforms the presence of Nitrogen.

3Na4[Fe(CN)6] + 4FeCl3 ---------------> Fe4[Fe(CN)6]3 (ferric cyanide) + 12NaCl

(if the product formed upon reacting with conc HCl gives Prussian blue or green colour 

then we can comform the presence of Nitrogen in given organic compound)

Sometimes during Nitrogen test there is the formation of blood red colour which shows the presence of both Nitrogen and sulphur in given organic compound. If the organic compound contains N as well as S during sodium fusion there will be the formation of NaCN instead NaCN which directly reacts with feric chloride solution to give ferric thio cynite which has blood red colour.

Na + S + C + N ---------------> NaCN (Sodium thio cyanide)

NaCN + FeCl3 ----------------> Fe(CNS)3 (ferric sulphocyanide, blood red)

Economic importance of Cyanobacteria | HSEB botany notes

Cyanobacteria are both useful as well as harmful to mankind and other living organism on the planet. The economic importance of cyanobacteria are as follows :

1. Cyanobacteria like Spriulina are cultivated in tanks as a protein rich food for fish and other animals.

2. Some blue green algae like Lyngbia can be used as antibiotics.

3. Species of cyanobacteria can grow on the walls and roofs of building during rainybseason causing discoloration, corrosion and leakage.

4. Nostoc sp benefits a number of plants with which it is associated by fixing nitrogen.

5. Even large colonies of Nostoc sp are edible.

Harmful effects :

6. Some cyanobacteria like Microcystis form water bloom on the surface of water and produce toxin ,and ultimatley pollute the water. The toxin is harmful to most aquatic animals and even to human beings.

Hseb Botany | Short notes on Archaebacteria

Archaebacteria is the most primitive and ancient bacteria. They are supposed to be oldest of the living fossils. They possess a unique cell wall that consists of polysaccharide and protein. They lack peptidoglycan (murein). The cell membrane contains branched-chain lipids, which enable them to withstand extremes of heat, high PH, absence of oxygen and high concentration.

Based upon ecological properties , the archaebacteria can be classified into three groups :

1. Thermoacidophiles (Temperature and acid loving) : They are aerobic forms of bacteria found in hot sulphur springs. They are high temperature and acid loving cyanobacteria. At 80 C, they oxidize sulphur to sulphuric acid in highly acidic medium. Under aerobic condition , these sulphur-dependent bacteria are called thermoacidophiles. These can reduce sulphur to H2S under anaerobic conditions.

2. Methanogens (Methane producers) : These are anaerobic archaebacteria which occur in marshy places and convert the formic acid or CO2 to methane. In biogas plants, they produce the methane gas, which is used as fuel.

3. Halophiles (Salt loving) : These are anaerobic bacteria which occur at salt rich soils. They prepare pigmented membrane in the presence of sunlight. This process is different from that of eukaryotic photosynthesis.

Manufacture of Ammonia by Haber's process | HSEB Chemistry notes

More on original site : Manufacture of Ammonia by Haber's process

Principle :  In this process , Ammonia is prepared from nitrogen and hydrogen. In ordinary condition , nitrogen do not react with hydrogen but when it is mixed with hydrogen in the ration 1:3 under 450 C temperature and 200-500 atm pressure in presence of Iron as catalyst and Molybdenum as promoter then it combines to form

Ammonia (NH3).

The reaction is exothermic, reversible and proceeding with decrease in volume. So, following condition is needed for better yield of it :

a. Low temperature : The reaction is exothermic , it as a rule is followed by low temperature. But if the temperature is very low then the rate of reaction will

be very slow and production of Ammonia will not be economically fruitful and beneficial. So optimum temperature of 450 C is maintained in this process.

b. high pressure : The reaction is reversible so it favored by high pressure. So pressure of about 200-500 atm is maintained.

c. High concentration : If the reactant are excess the the product formed will also be same . So either hydrogen or nitrogen in the reactant side is made excess to 

produce high amount of ammonia.

d. Use of catalyst : In absence of catalyst, the reaction will be slow. So, Iron is used as catalyst along with molybdenum as promoter to increase the rate of reaction

without hampering it. 

Process : In this process, N2 is treated with H2 in the ratio 1:3 . Then the gaseous mixture is passed through compressor in which pressure of 200-500 atm is applied.

Then the gases mixture is passed through catalyst chamber packed with finely divided Iron + molybdenum. The chamber is initially heated to about 450 C to initiate the 

reaction. During this condition , 15% of the gaseous mixture is turned into ammonia. Thus , the gaseous coming out of the chamber contains NH3 and unreacted H2 and N2. These are then passed through condenser to condense only ammonia not H2 and N2. The liquefied ammonia is collected at the bottom from time to time. The other uncombined 

H2 and N2 is recycled and reprocedded. 

Nervous system of earthworm zoology | HSEB | Grade 11 zoology notes

The system which controls , regulate and co-ordinate the functioning of all organ of the body is called as nervous system. In earthworm , nervous system is well developed and divided into following parts :

1.   Central nervous system :

It consists of ventral nerve chord lying ventrally to the alimentary canal in the middle line. It starts from anterior end (from 3td segment) and extends throughout the whole length of the body.  It enlarges in each segment to form swelling called ganglia. In the anterior end of 3rd segment or dorsal side of pharynx , there is presence of bilobed swelling called cerebral ganglia or suprapharyngeal ganlia which is also called the brain of the earthworm. The ganglia lies below the suprapharyngeal ganglia is know as the sub-pharyngeal ganglia. In earthworm , supra-pharyngeal ganglia and circum-pharyngeal connective together form the nerve ring. It lies in 3rd and 4th segment.

2.   Pheripheral nervous system :

The nerve arising from supra-pharyngeal , circum-pharyngeal  , sub-pharyngral ganglia and other segmental ganglia together form pheripheral nervous system. From cerebral ganglia , 8-10 nerve arise which divide into branches that passes through prostomium , pharynx and buccal cavity. From circum-pharyngeal ganglia 2 pair of nerve arises which passes into buccal cavity and pharynx. From sub-pharyngeal ganglia, three pair of nerve arises which passes into 2nd, 3rd and 4rd segment. Behind 4rd segement , in each segment 3 pair of nerve arises. Among them , 1 arise near anterior end of each segment and other 2 ftom the swelling caled present in each segment of body of earthworm.

3. Autonomic nervous system : It consists of extensive nerve plexus beneath epidermis in musculature of body wall and on alimentary canal.

Grade 11 | 2073 English exam question paper

Grade 11 | 2073 physics exam question paper

This is 2073 B.S (2017 A.D) second term question paper. This exam was conducted by Nepal Education Foundation (NEF). I took this exam from Xavier academy as I learn there. Hope this helps you to practice for HSEB board exam  :) .

Grade 11 | Physics 2nd term question paper of Nepal Education Foundation

Year 2067 B.S

 

Year 2068 B.S

Year 2069 B.S 

Year 2070 B.S 

Year 2071 B.S

Year 2072 B.S

Economic importance of earthworm.

More on original Site : ohonotes.com/economic-importance-of-earthworm.html

Earthworms are both useful and harmful to mankind.

Useful aspects

1. It burrows the land makes the soil surface porous. This enhances the fertility of soil and growth of plant occurs well.

2. It is eaten as food in different countries of the world.

3. It is also used as medicine in curing stones in gal bladder , diarrhoea , jaundice , pills etc.

4. It is used as bait in fishing.

5. It is used in zoology lab for disection purpose.

6. It is used in making compoat manure called vermicompostion.

Harmful aspects

1. The casting or pallets excreted by earthworm in slopy land are washed away by rain which contribute to soil erosion.

2. It destroys tender plant in fields and garden by eating them.

HSEB zoology notes : Types of fossils

On the basis of organism body preserved fossils are of following types :

1. Intact or entire or unalterated fossils : They are those type of fossil in which entire organism or part of their body is buried in the dry and cold region of the world. For eg : fossil of ancient elephant (mammoths) found in frozen ice of siberia. Insects embedded in amber.

2. Petrification or Petrified fossil : It is the type of fossil in which hard part of organism like teeth , skeltion, shells of mollusca , branches of trees etc remain preserved.

3. Mould or casts : They are those type of fossils in which impression of organism is only left bend. Even the skeletion devays leaving impression only which is the exact replica or copy of original organism.

4. Compression : It is the most usual type of plant fossil in which internal structure of plant is totally lost and thin carbon film giving outline of the plant is left behind.

5. Imprints or impression : It is formed due to footfrints of crawling worm or snail.

6. Pseudo fossil : It is false fossil which give impression but are not real fossil. For eg : In certain rocks , a structure are present which resembles the plant remain and are formed by crystallization of minerals found in crevices of rocks.

Archaeopteryx is a connecting link between reptiles and birds, Justify.

More on Original site : Archaeopteryx is a connecting link between reptiles and birds.

Archaeopteryx lithographica is the connecting link between aves and reptile. It is fossil bird found in rocks of jurassic period by Andreas Wagner. It's fossil is still kept in the muesuem of Berlin and London. It's appearance and size were like that of crow but had both characters of aves and reptiles suggesting that aves have been evolved from reptile.

It's characters were as follows :

1. It had beak like bird but had teeth and heavier jaws like reptile.
2. It's forelimbs were modified into wings but had claws on wings like reptile.
3. It had feathers like bird but also had scales like reptile.
4. It had feathery tail like bird but tail vertebrae like reptile.

Nomenclature of some organic compound