NIOS Class 12th Chemistry English Medium Solve Assignment (TMA) 2021

 Chemistry (313)

Tutor Marked Assignment

Max.Marks: 20

1. Answer any one of the following questions in about 40-60 words.

(b) Although the size of sulfur is smaller than phosphorous first ionization enthalpy of phosphorous is more than sulfur. Why?

Ans- 

> Ionization energy is the amount of energy required to remove an electron from Neutral gaseous electrons.

> Across period, in a periodic table from left to right LE, should increase.

> Third-period elements are Na, Mg. Al, Si, P, S, CI, Ar 

> Order of LE in the third period: NacMg>Aksi<P<S<CI<Ar

> third-period element with the highest ionization energy is argon due to stable Octet configuration.

• Case 1: Mg has more LE than AL. Mg,>AI

> due to its stable ns2 configuration of Mg. In 

• Case 2:

> P has more LE than sulfur (S) because phosphorous has a half-filled p subshell in its valence shell that gives extra stability and hence more energy is required to remove the electron.

2. Answer any one of the following questions in about 40-60 words.

(b) What type of semiconductor obtained when Si or Ge are doped with elements of group 13 such as B or Al and why?

Ans- 

> The addition small amount of foreign impurity in the host crystal is called Doping

> It results in an increase in the electrical conductivity of the crystal.

> Doping of group 14 elements (such as Si, Ge, etc.) with elements of group 15 (such as As) produces an excess of electrons in the crystals.

> Thus, It gives n-type semiconductors.

> Doping of groups 14 elements with group 13 elements (such as Indium) Produces holes (electron deficiency) in the crystals.

> Thus, p-type semiconductors are produced.

> The symbol p’ indicates the flow of positive charge.

3. Answer any one of the following questions in about 40-60 words.

(a) Explain with example reversible and irreversible reactions.

Ans-

4. Answer any one of the following questions in about 100-150 words.

(a) (i) What is the relationship between the standard Gibbs energy change and the equilibrium constant of the reaction.

(ii) Differentiate between physical and chemical adsorptions.

Ans- (i) What is the relationship between the standard Gibbs energy change and the equilibrium constant of the reaction.

> The free energy change of the reaction in any state, ∆G (when equilibrium has not been attained) is related to the standard free energy change of the reaction, ∆G0 (which is equal to the difference in free energies of formation of the products and reactants both in their standard states) according to the equation.

∆G = ∆G⁰ + RT InQ.

• Where Q is the reaction quotient

  > When equilibrium is attained, there is no further free energy change i.e. ∆G = 0, and Q becomes equal to the equilibrium constant. Hence the above equation Becomes.

∆G⁰ = -RT in k(eq)

Or ∆G⁰ = -2.303 RT log K(eq)

> In the case of galvanic cells. Gibbs energy change AG is related to the electrical work done by the cell.

∆G= - nFE(cell)

• Where n = no. of moles of electrons involved
• F= the Faraday constant
• E = emf of the cell

  > If reactants and products are in their standard states

∆G⁰ = - nFE(cell)

Ans- (ii) Differentiate between physical and chemical adsorptions.

5. Answer any one of the following questions in about 100 to 150 words.

(b) Identify the Vitamins in each case whose deficiency causes the following symptom.

(i) Anaemia

(ii) Depression

(iii) Dry skin

(iv) Osteomalacia

(2) Give Two examples of artificial sweetening agents.

Ans- Anemia:

> Vitamin deficiency anemia happens when there are fewer healthy red blood cells in the body than normal. This condition caused by a lack of vitamins. The risk of developing vitamin deficiency anemia increases with age and during pregnancy.

• What is vitamin deficiency anemia?

  > Vitamin deficiency anemia occurs when the body has fewer healthy red blood cells than is normal. Red blood cells help deliver oxygen to organs and tissues all over the body. When you don't have enough red blood cells, your body does not get the amount of oxygen it needs.

• How common is vitamin deficiency anemia?

  > The risk of developing vitamin deficiency anemia gets higher as you grow older. Pregnant women are at a higher risk for developing the condition because their bodies need more vitamins during pregnancy.

• _{v   What causes vitamin deficiency anemia?}

  > A lack of any one of several vitamins – B12, folate (also known as folic acid). or vitamin C – causes vitamin deficiency anemia. Megaloblastic anemia is a type of vitamin deficiency anemia that specifically involves a lack of vitamin B12 or folate.

   > Some people with the condition don’t eat enough of these vitamins. In other cases, the person’s body cannot properly process or absorb these vitamins. This difficulty may result from an underlying condition such as celiac disease. It is also linked to behaviors including smoking and alcohol abuse.

   > Sometimes a person's body will have an increased need for these vitamins. People who need more of these vitamins include women who are pregnant and people with cancer that has spread to multiple parts of their bodies. If they do not meet this additional need for vitamins, they can develop vitamin deficiency Sometimes a person’s body will have an increased need for these vitamins anemia.

• What are the symptoms of vitamin deficiency anemia?

  > Symptoms of vitamin deficiency anemia are often mild, In many cases, people only discover they have the condition when a doctor tests them for another condition. Other people may develop symptoms that include: 

  > Extreme tiredness (fatigue), Weakness, Dizziness, Pale skin, Shortness of breath Irregular heartbeat, Numbness or cold feeling in hands and feet

• Depression: 

  > Vitamin A deficiency can result from inadequate intake, fat malabsorption, or liver disorders. Deficiency impairs immunity and hematopoiesis and causes rashes and typical ocular effects (eg, xerophthalmia, night blindness). Diagnosis based on typical ocular findings and low vitamin A levels. Treatment consists of vitamin A given orally or, if symptoms are severe or malabsorption is the cause, parenterally.

  > Vitamin A is required for the formation of rhodopsin, a photoreceptor pigment in the retina (see table Sources, Functions, and Effects of Vitamins). Vitamin A helps maintain epithelial tissues and is important for lysosome stability and glycoprotein synthesis,

  > Dietary sources of preformed vitamin A include fish liver oils, liver, egg yolks, butter, and vitamin A-fortified dairy products. Beta-carotene and other provitamin carotenoids, contained in green leafy and yellow vegetables, carrots, and deep- or bright-colored fruits, are converted to vitamin A.

  > Carotenoids are absorbed better from vegetables when they are cooked or homogenized and served with some fat (eg, lots). Normally, the liver stores 80 to 90% of the body’s vitamin A. To use vitamin A, the body releases it into the circulation bound to prealbumin (transthyretin) and retinol-binding protein.

  > Retinol activity equivalents (RAE) were developed because provitamin A carotenoids have less vitamin A activity than preformed vitamin A: 1 meg retinol 3.33 units.

  > Synthetic vitamin analogs (retinoids) are being used increasingly in dermatology. The possible protective role of beta-carotene, retinol, and retinoids against some epithelial cancers is under study. However, the risk of certain cancers may be increased after beta-carotene supplementation.

  > Primary vitamin A deficiency is usually caused by

• Prolonged dietary deprivation

  > Keratinization of the skin and of the mucous membranes in the respiratory, gastrointestinal, and urinary tracts can occur. Drying, scaling, and follicular thickening of the skin and respiratory infections can result.

  > Immunity is generally impaired.

  > The younger the patient, the more severe are the effects of vitamin A deficiency. Growth retardation and infections are common among children. The mortality rate can exceed 50% in children with severe vitamin A deficiency

• Key Points:

  > Vitamin A deficiency usually results from dietary deficiency, as occurs in areas where rice, devoid of beta-carotene, is the staple food, but it may result from disorders that interfere with the absorption, storage, or transport of vitamin but

  > Ocular findings include impaired night vision (early), conjunctival deposits, and keratomalacia.

  > In children with severe deficiency, growth is slowed and risk of infection is increased.

  > Diagnose based on ocular findings and serum retinol levels.

  > Treat with vitamin A palmitate. 

• Dry skin:

  > Vitamin D deficiency: There are several other important functions of vitamin D for your overall health. One may experience different symptoms due to vitamin D deficiency. Some symptoms are visible on your skin like dry skin.
  > Vitamin D, the sunshine vitamin is known for maintaining the health of your bones and teeth. This vitamin helps in the absorption of calcium you get from your diet. It offers several other benefits like supporting immunity, the health of a nervous system, diabetes management, better lung, and cardiovascular health, and much more.
  > Certain surgeries: Normally, the stomach breaks down food to release calcium and other minerals that are absorbed in the intestine. This process is disrupted if you have surgery to remove part or all of your stomach or to bypass your small intestine and can result in vitamin D and calcium deficiency.

  > Celiac disease: In this autoimmune disorder, foods containing gluten, a protein found in wheat, barley, and rye, can damage the lining of your small intestine. A damaged intestinal lining doesn’t absorb nutrients well and can lead to vitamin D and calcium deficiency.

  > Kidney or liver disorders: These organs are involved in activating vitamin D in your body. Problems with your kidneys or liver can affect your body’s ability to make active vitamin D.

  > Drugs: Some drugs used to treat seizures, including phenytoin (Dilantin, Phenytek) and phenobarbital, can cause severe vitamin D deficiency and osteomalacia.

6. Visit the nearby treatment process of Sewage and collect the following knowledge/ information.

(i) How many stages are there of treatment of wastewater?

(ii) What is coagulation?

(iii) What is substance?

(iv) What is softening?

(v) Which is used as a disinfectant to kill bacteria?

(vi) How chlorine produces toxic and potential carcinogens?

Ans- 

• How many stages are there of treatment of wastewater?

  > Drinking water treatment ponds

  > Stormwater treatment ponds

  > Municipal wastewater treatment ponds

• What is coagulation?

  > flocculation is a chemical water treatment technique typically applied prior to sedimentation and filtration (e.g. rapid sand filtration) to enhance the ability of a treatment process to remove particles. Coagulation is a process used to neutralize charges and form a gelatinous mass to trap (or bridge) particles thus forming a mass large enough to settle or be trapped in the filter. Flocculation is gentle stirring or agitation to encourage the particles thus formed to agglomerate into masses large enough to settle or be filtered from the solution.

• Advantages:

  > Simplicity and cost-effectiveness

  > Separates many kind of particles from water

  > Enhances filtration process

  > Uses abundant and low cost chemicals

  > Physical processes for mechanical preparation such as aeration, sedimentation or thermal influence. This also includes the use of screens, filters, and sieves.

  > Biological processes such as anaerobic wastewater treatment, biochemical oxidation or sludge digestion.

  > Chemical processes such as neutralization, disinfection, flocculation, and precipitation.

  > Membrane processes such as filtration, osmosis, and nanofiltration.

• What is softening?
• Step 1: Screening and Pumping

  > The incoming wastewater passes through screening equipment where objects such as rags, wood fragments, plastics, and grease are removed. The material removed is washed and pressed and disposed of in a landfill. The screened wastewater is then pumped to the next step: grit removal. 

• Step 2: Grit Removal

  > In this step, heavy but fine material such as sand and gravel is removed from the wastewater. This material is also disposed of in a landfill.

• Step 3: Primary Settling

  > The material, which will settle, but at a slower rate than step two, is taken out using large circular tanks called clarifiers. The settled material, called primary sludge, is pumped off the bottom and the wastewater exits the tank from the top. Floating debris such as grease is skimmed off the top and sent with the settled material to digesters. In this step, chemicals are also added to remove phosphorus.

• Step 4. Aeration Activated Sludge

  > In this step, the wastewater receives most of its treatment. Through biological degradation, the pollutants are consumed by microorganisms and transformed into cell tissue, water, and nitrogen. The biological activity occurring in this stop is very similar to what occurs at the bottom of lakes and rivers, but in these areas, the degradation takes years to accomplish.

• Step 5: Secondary Settling

  > Large circular tanks called secondary clarifiers to allow the treated wastewater to separate from the biology from the aeration tanks at this step, yielding an affluent, which is now over 90% treated. The biology (activated sludge) is continuously pumped from the bottom of the clarifiers and returned to the aeration tanks in step four.

• Step 6: Filtration

  > The clarified effluent is polished in this step by filtering through 10-micron polyester media. The material captured on the surface of the disc filters is periodically backwashed and returned to the head of the plant for treatment.