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Statement (A) : Symbol of carbon is ‘C’ ...

Statement (A) : Symbol of carbon is ‘C’ whereas symbol of calcium is ‘Ca’. Reason (R) : Eventhough carbon and calcium have ‘C’ as its initial, carbon occurs first in periodic table. So, its symbol was taken as ‘C’ and calcium symbol was taken as ‘Ca’.

A

Both A and R are true

B

Both A and R are false

C

A is true but R is false

D

A is false but R is true

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Heating of calcium carbonate a) Write the chemical equation to it. b) Which type of reaction is it ? c) Give another example for same type of reaction.

Assertion (A):Carbon cannot for C^4- ions so easily.Reason (R):It would be difficult for a nucleus with six protons to hold ten electrons.

Knowledge Check

  • 50 grams of calcium carbonate was completely burnt in air. What is the weight (in grams) of the residue? Atomic weights of Ca, C and O are 40,12 and 16 respectively)

    A
    2.8
    B
    28
    C
    22
    D
    4.4

  • (A): C Cl_(2) does not undergo hydrolysis where as SiCl_(4) is readily hydrolysed. (R) : Carbon has no d-orbitals in its valence shell, but silicon has vacant d-orbitals in its valence shell.

    A
    a. Both A and R are true, and R is correct explanation of A
    B
    b. Both A and R are true, and R is not correct explanation of A
    C
    c. A is true, but R is false
    D
    d. A is false, but R is true

  • Consider the following statements (A) Gypsum contains a low percentage of calcium than plaster of paris (B) Plaster of paris can be reobtained by hydration of dead plaster (C ) Gypsum looses 3//2 of its water of crystallisation formes plaster of paris at 120^(@)C (D) Plaster of paris can be obtained by partial oxidation of gypsum Arrange them in the order of true/false

    A
    TFTF
    B
    "FF"TF
    C
    "TT""FF"
    D
    "TTTT"

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    The necessary condition for a molecule to exhibit optical isomerism is dissymmetry or chiral. Thus all organic compounds which contain one as symetric carbon atom are chiral and exist in two stereoisomers. Although the two forms have the same structure, they have different arrangements of groups about the as symmetric carbon. In fact, they represent as symetric molecules. They do not have a plane of symmetry. They are related to each other as an object to its mirror image and are non superimposable. The two structures actually stand for dextro or (+) and leavo or (-) isomers. Since they are related each other as mirror images, they are commonly called enantiomers. Consider the following structures A,B,C,D Which of the following statements is not correct

    The necessary condition for a molecule to exhibit optical isomerism is dissymmetry or chiral. Thus all organic compounds which contain one assymetric carbon atom are chiral and exist in two stereoisomers. Although the two forms have the same structure, they have different arrangements of groups about the assymmetric carbon. In fact, they represent assymetric molecules. They do not have a plane of symmetry. They are related to each other as an object to its miror image and are non superimposable. The two structures actually stand for dextro or (+) and leavo or (-) isomers. Since they are related each other as mirror images, they are commonly called enantiomers. Consider the following structers A,B,C,D Which of the following statements is not correctConsider the following structers A,B,C,D Which of the following statements is not correct

    alpha - amino acids are high melting crystalline solids because of the zwitterion structure. They are moderately soluble in water. In acidic medium, alpha - amino acids exist as cations (I) and thus migrate towards cathode under the influence of an electric field. On the other hand, in alkaline medium, alpha - amino acids exist as anions (III) and thus migrate towards anode under the influence of an electric field. However, at some intermediate value of p^(H) , the concentration of the cationic form (I) and anionic form (III) will become equal and consequently the alpha - amino acid will exist primarily as the neutral dipolar ion (II). At this p^(H) , there would be no net migration of the amino acid in an electric field. This p^(H) at which there is no net migration of the amino acid under the influence of an applied electric field is called isoelectric point (pI). Each amino acid has a characteristic isoelectric point. The pH of an amino acid that does not have an ionisable side chain such as alanine isd average of pK_(a) values of the carboxyl group and the protonated amino group. H_(3)overset(+)(N)-overset("R")overset("|")("C")H-COOH overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr H_(3)overset(+)(N)-underset("Zwitterion (II)")(overset("R")overset("|")("C")H)-COO^(-)overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr underset((III))(overset(+)(N)-overset("R")overset("|")("C")H)-COO^(-) Further, the alpha - carbon of all the amino acids (except glycine) is chiral (asymmetric) and hence amino acids can exist in teo stereoisomeric forms i.e., D and L. However, all the nautrally occurring amino acids belong to the L - series. underset("L(-)Glyceraldehyde")(HO-overset("CHO ")overset("| ")underset(" "CH_(2)OH)underset("| ")("C ")-H)" " underset("L-Amino acid")(H_(2)N-overset("COOH")overset("| ")underset("R ")underset("| ")("C ")-H) Which of structural formula of lysine (NH_(2)-overset("COOH")overset("| ")("C ")H-CH_(2)-CH_(2)-CH_(2)-CH_(2)NH_(2)) at pH 13 ?

    alpha - amino acids are high melting crystalline solids because of the zwitterion structure. They are moderately soluble in water. In acidic medium, alpha - amino acids exist as cations (I) and thus migrate towards cathode under the influence of an electric field. On the other hand, in alkaline medium, alpha - amino acids exist as anions (III) and thus migrate towards anode under the influence of an electric field. However, at some intermediate value of p^(H) , the concentration of the cationic form (I) and anionic form (III) will become equal and consequently the alpha - amino acid will exist primarily as the neutral dipolar ion (II). At this p^(H) , there would be no net migration of the amino acid in an electric field. This p^(H) at which there is no net migration of the amino acid under the influence of an applied electric field is called isoelectric point (pI). Each amino acid has a characteristic isoelectric point. The pH of an amino acid that does not have an ionisable side chain such as alanine isd average of pK_(a) values of the carboxyl group and the protonated amino group. H_(3)overset(+)(N)-overset("R")overset("|")("C")H-COOH overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr H_(3)overset(+)(N)-underset("Zwitterion (II)")(overset("R")overset("|")("C")H)-COO^(-)overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr underset((III))(overset(+)(N)-overset("R")overset("|")("C")H)-COO^(-) Further, the alpha - carbon of all the amino acids (except glycine) is chiral (asymmetric) and hence amino acids can exist in teo stereoisomeric forms i.e., D and L. However, all the nautrally occurring amino acids belong to the L - series. underset("L(-)Glyceraldehyde")(HO-overset("CHO ")overset("| ")underset(" "CH_(2)OH)underset("| ")("C ")-H)" " underset("L-Amino acid")(H_(2)N-overset("COOH")overset("| ")underset("R ")underset("| ")("C ")-H) In alanine, carboxyl group ionises at pK_(a1)=2.34 and ammonium ion at pK_(a2)=9.69 . The isoelectric point of the amino acid is at p^(H) .

    alpha - amino acids are high melting crystalline solids because of the zwitterion structure. They are moderately soluble in water. In acidic medium, alpha - amino acids exist as cations (I) and thus migrate towards cathode under the influence of an electric field. On the other hand, in alkaline medium, alpha - amino acids exist as anions (III) and thus migrate towards anode under the influence of an electric field. However, at some intermediate value of p^(H) , the concentration of the cationic form (I) and anionic form (III) will become equal and consequently the alpha - amino acid will exist primarily as the neutral dipolar ion (II). At this p^(H) , there would be no net migration of the amino acid in an electric field. This p^(H) at which there is no net migration of the amino acid under the influence of an applied electric field is called isoelectric point (pI). Each amino acid has a characteristic isoelectric point. The pH of an amino acid that does not have an ionisable side chain such as alanine isd average of pK_(a) values of the carboxyl group and the protonated amino group. H_(3)overset(+)(N)-overset("R")overset("|")("C")H-COOH overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr H_(3)overset(+)(N)-underset("Zwitterion (II)")(overset("R")overset("|")("C")H)-COO^(-)overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr underset((III))(overset(+)(N)-overset("R")overset("|")("C")H)-COO^(-) Further, the alpha - carbon of all the amino acids (except glycine) is chiral (asymmetric) and hence amino acids can exist in teo stereoisomeric forms i.e., D and L. However, all the nautrally occurring amino acids belong to the L - series. underset("L(-)Glyceraldehyde")(HO-overset("CHO ")overset("| ")underset(" "CH_(2)OH)underset("| ")("C ")-H)" " underset("L-Amino acid")(H_(2)N-overset("COOH")overset("| ")underset("R ")underset("| ")("C ")-H) N - terminus of the peptide structure is on the

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