Showing posts with label chemistry 12th grade. Show all posts
Showing posts with label chemistry 12th grade. Show all posts

Sunday, July 18, 2021

What are the important sources of organic compounds?

 The main sources of organic compounds are plant and animal kingdoms. Organic compounds are isolated from these two natural sources by solvent extraction followed by purification. These two sources are again converted naturally into petroleum oil, natural gas, and coal. Organic compounds always contain carbon along with other elements that are needed for living organisms to function. All organic compounds are one time came from plants or animals many of our most important substance are still derived from these sources directly or indirectly.

Nowadays synthesis is the most important source of organic compounds. So, the sources of organic compounds, in short, are-

Plants and animals: By using suitable methods of isolation most of the organic compounds were obtained directly from plants and animals in the past and at present, these methods are continuing. Many organic compounds are obtained straightforwardly from plant and animals sources by a suitable method of isolation a few common examples are carbohydrates (cellulose, sugar, and starches) proteins (silk, wool, casein, and food proteins) fats and oils (cottonseed soybean oils lard, butter) alkaloids (quinine, morphine, strychnine) hormones, vitamins, perfumes, flavors and resins. There are four major categories are found in all living things: carbohydrates, lipids, proteins, and nucleic acids. The compounds which are obtained from these sources are –

  • Carbohydrates: Cellulose, starch, sugar, lactose, etc.
  • Protein: Food proteins, wool, silk, casein, etc.
  • Fats and oils: Cottonseed, soya bean oil, lard, butter, etc.
  • Alkaloids: Quinine, morphine, ephedrine, etc.
  • Perfumes: Citral, limonen, mascone, etc.
  • Vitamins: Vit. C, B2, B6, etc.
  • Hormones, Resins, rubber, etc.
Petroleum oil and natural gasHundreds of hydrocarbons such as methane, octane, kerosene, petrol, benzene, toluene and other petrochemicals are obtained which are further used as raw materials of polymers, plastics, synthetic rubber, explosives, etc. Natural gas and petroleum are now the key sources of organic compounds they are used as fuels and also, through the synthetic organic reaction for the production of hundreds of valuable organic substances such as solvents, synthetic rubber, explosive, and plastic. The main energy source, fuel is obtained from natural gas and crude petroleum oil. Urea is a good example which is obtained from natural gas on our planet.

Coal: Another fossil fuel coal is the major source of organic compounds, coal-tar are raw materials of many aromatic compounds. Coal is another key source of organic compounds. It yields coke and coal-tar on hydrolysis or destructive distillation more than 200 organic compounds have been in a straight line isolated from coal-tar, these coal-tar products from the starting resources for the manufacture of thousands of helpful aromatic compounds, including perfumes, drugs, dyes, photographic developers, and other.

Synthesis: Simple organic compounds resulting from petroleum or coals have been transformed into thousands of helpful resources by a synthetic process. Many useful organic compounds including drugs, vitamins, plastics, dyes, etc. are prepared from simple raw materials by multistep synthesis. Many examples might be cited of synthetic organic compounds replacing those obtained from natural sources, such as dyes, rubber, fibers, plastic, drugs, vitamins in many cases the synthetic materials are better to the natural compounds replaced for example, synthetic dyes are greater to those of usual source in other cases the synthetic resources are completely unidentified in nature and fill the requirements not contented are completely other sources. Examples are ether glycol; aspirin, and sulfur drugs, synthetic organic chemistry touches almost every phase of life.

Hence, the important sources of organic compounds are plant and animal kingdoms.

Sunday, June 27, 2021

Bleaching action of H2O2 is due to its : (A) Oxidizing nature (B) Reducing nature (C) Acidic nature (D) Thermal instability

Question:

Bleaching action of H2O2 is due to its : 

(A) Oxidizing nature 

(B) Reducing nature 

(C) Acidic nature 

(D) Thermal instability

Answer: option (1) " oxidizing nature"

Explanation:

It acts as bleaching agent due to the release of nascent oxygen. Thus, the bleaching action of hydrogen peroxide is permanent and it is due to oxidation. It oxidizes the coloring matter to a colorless product. 

H2O2  H2O + [O]

Hence, option (1) " oxidizing nature" is the correct answer.

Antimarkonikov's addition of HBr is not observed in (A) Propene (B) But-1-ene (C) but-2-ene (D) Pent-2-ene

Question:

Antimarkonikov's addition of HBr is not observed in 

(A) Propene 

(B) But-1-ene 

(C) but-2-ene 

(D) Pent-2-ene 

Answer: option (C) but-2-ene

Explanation:

The Anti-Markovnikov's addition is also called the peroxide effect or the Kharasch effect. The Anti-Markovnikov's rule states that, in the presence of peroxide like benzoyl peroxide (C6H5CO-O-O-COC6H5), the addition of HBr to unsymmetrical alkenes takes place contrary to the Markovnikov's rule. In Markovnikov's rule, the negative part of the addendum gets attached to the carbon atom in the double bond which has a lesser number of a hydrogen atom or more substituted carbon atom. So, in Anti- Markovnikov's rule, the negative part of the addendum gets attached to the carbon atom in the double bond which has more number of hydrogen atoms. 

(A) Propene: The formula of Propene is CH2=CH-CH3. This is an unsymmetrical alkene. So according to the Anti- Markovnikov's rule, the negative part will attach the carbon atom with 2 hydrogen atoms. 

(B) But-1-ene: The formula of But-1-ene is CH2=CH-CH2-CH3. This is an unsymmetrical alkene. So according to the Anti- Markovnikov's rule, the negative part will attach the carbon atom with 2 hydrogen atoms.

(C)- But-2-ene: The structure of 2-Butene is CH3-CH=CH-CH3. This is a symmetrical alkene and the Anti- Markovnikov's rule will not be observed in 2-Butene. 

(D)- pent-2-ene The structure of 2-Pentene is CH3-CH=CH-CH2-CH3. This is an unsymmetrical alkene. So according to the Anti- Markovnikov's rule, the negative part will attach the carbon atom with the methyl group because it is less substituted. 

Hence, option (C) "But-2-ene" is the correct answer.

Tuesday, June 22, 2021

The property which regularly increases down the group in the periodic table is : (a) lionization enthalpy (b) Electronegativity (c) Reducing character (d) Electron gain enthalpy.

Question: 

The property which regularly increases down the group in the periodic table is : 

(a) lionization enthalpy 

(b) Electronegativity 

(c) Reducing character 

(d) Electron gain enthalpy.

Answer: option (c) " Reducing character"

Explanation:

The metallic character is used to define the chemical property that metallic elements present. Generally, metals tend to lose electrons to form cations. Nonmetals tend to gain electrons to form anions. They also have a high oxidation potential therefore they are easily oxidized and are strong reducing agents. Thus the property which regularly increases down the group in the periodic table is Reducing nature. 

Hence, option (c) " Reducing character" is the correct answer.

Monday, June 21, 2021

Schottky defect is observed in crystals when.....

Question:

Schottky defect is observed in crystals when.....

Answer: when equal numbers of cations and anions are missing from the lattice.

Explanation:

Schottky defect in crystals is observed when equal numbers of cations and anions are missing from the lattice. It is important that an equal number of cations and anions are missing, otherwise the electrical neutrality of the crystal will get affected.

Hence, Schottky defect is observed in crystals when equal numbers of cations and anions are missing from the lattice.


Number of water molecules consumed by one of P4O10 to undergo complete hydrolysis in order to produce ortho phosphoric acid is....

   Question: 

   Number of water molecules consumed by one of P4O10 to             undergo complete hydrolysis in order to produce ortho                 phosphoric acid is....

   Answer: 6



Sunday, June 20, 2021

valance electron of sodium and magnesium are (a) 1 and 2 (b) 1 and 3 (c) 1 and 4 (d) 1 and 5

Question:

valance electron of sodium and magnesium are 

(a) 1 and 2 

(b) 1 and 3 

(c) 1 and 4 

(d) 1 and 5 

Answer: option (a) 1 and 2

Explanation:

The electrons in the outermost shell are the Valence electrons. These are the electrons in An atom that can participate in a chemical Reaction. 

The electron configuration for sodium (Na) is: 

1s²2s²2p⁶3s¹ 

The outer energy level for this atom is n = 3, And it has one electron in this energy level. Therefore, Sodium has one valence Electrons. 

The electron configuration for magnesium is: 

1s²2s²2p⁶3s²

The outer energy level for this atom is n = 3, And it has two electrons in this energy level. Therefore, magnesium has two valence Electrons. So, Valance electron of sodium and magnesium Are 1 and 2 respectively. Hence, the correct answer is option (a) 1 and 2.

Hence the answer is (A) 1 and 2


Sunday, June 13, 2021

Ethoxy ethane and methoxy propane are (A) Geometrical isomers (B) Optical isomers (C) Functional group isomers (D) Metamers

Question: 

Ethoxy ethane and methoxy propane are 

(A) Geometrical isomers 

(B) Optical isomers 

(C) Functional group isomers 

(D) Metamers

Answer:

Correct option: (D) Metamers

Explanation:

Structure of Ethoxyethane:

CH₃-CH₂-O-CH₂-CH₃

Structure of Methoxy propane:

CH₃-O-CH₂-CH₂-CH₃

Ethoxy ethane and Methoxy propane are metamers. Because, both are isomeric ethers but oxygen is attached to different alkyl groups in two compounds. Ethoxyethane and Methoxy propane are metamers. Because, both are isomeric ethers but oxygen is attached to different alkyl groups in two compounds.

Hence, option (D) "Metamers" is the correct answer.

If two liquids A and B have P_A^o:P_B^o=1:2 and have mole fraction in solution 1:2, then mole fraction of Ain vapour is (1) 0.33 (2) 0.25 (3) 0.52 (4) 0.2

 





Friday, June 11, 2021

Antimarkonikov's addition of HBr is not observed is (a) Propene (b) But-1-ene (c) But-2-ene (d) Pent-2-ene

Question: 

Antimarkonikov's addition of HBr is not observed is 

(a) Propene 

(b) But-1-ene 

(c) But-2-ene 

(d) Pent-2-ene

Answer:

Correct option: (c) But-2-ene

Explanation:

The Anti-Markovnikov's addition is also called the peroxide effect or the Kharasch effect. The Anti-Markovnikov's rule states that, in the presence of peroxide like benzoyl peroxide ( C₆H₅CO–O–O-COC₆H₅), the addition of HBr to unsymmetrical alkenes takes place contrary to the Markovnikov's rule. In Markovnikov's rule, the negative part of the addendum gets attached to the carbon atom in the double bond which has a lesser number of a hydrogen atom or more substituted carbon atom. So, in Anti- Markovnikov's rule, the negative part of the addendum gets attached to the carbon atom in the double bond which has more number of hydrogen atoms.

(A)- Propene: 

The formula of Propene is CH₂=CH–CH₃. This is an unsymmetrical alkene. So according to the Anti- Markovnikov's rule, the negative part will attach the carbon atom with 2 hydrogen atoms.

(B)- But-1-ene: 

The formula of But-1-ene is CH₂=CH–CH₂–CH₃. This is an unsymmetrical alkene. So according to the Anti- Markovnikov's rule, the negative part will attach the carbon atom with 2 hydrogen atoms.

(C)- But-2-ene:

The structure of 2-Butene is CH₃-CH=CH–CH₃. This is a symmetrical alkene and the Anti- Markovnikov's rule will not be observed in 2-Butene.

(D)- pent-2-ene: 

The structure of 2-Pentene is CH₃–CH=CH–CH₂–CH₃. This is an unsymmetrical alkene. So according to the Anti- Markovnikov's rule, the negative part will attach the carbon atom with the methyl group because it is less substituted.

Hence, option (c) "But-2-ene" is the correct answer.

What are pseudo first order reactions? Give one example and explain why it is pseudo first order.

Question: 

What are pseudo first order reactions? Give one example and explain why it is pseudo first order.

Explanation:

Pseudo first-order reaction: 

Reaction which appears to be a second-order reaction, but actually is the first-order reaction is called pseudo-first-order reaction. This condition occurs in a chemical reaction between two substances when one reactant is present in a large amount. The concentration of reactant present in excess does not get altered much during the course of the reaction. Due to this reaction behaves as the first-order reaction.

Example:

Hydrolysis of esters

CH₃COOC₂H₅ + H₂O  CH₃COOH + C₂H₅OH

Rate law for this reaction is;

Rate K[CH₃COOC₂H₅][H₂O]

But the concentration of water does not change during the course of the reaction. 

So; [H₂O] is constant.

Therefore rate=K₁[CH₃COOC₂H₅]

Where, K=K'[H₂O]

So, the reaction behave as a first order reaction.

What is Mutualism? write type and example.

Question: What is Mutualism? write type and example. Answer: Mutualism: The term mutualism can be simply defined as a relationship in which ...