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Alkoxides of beryllium [Be(OR)(2)](6) us...

Alkoxides of beryllium `[Be(OR)_(2)]_(6)` usually have associated strutures with both `mu_(2)` - bridging and terminal OR groups. For example `[Be(OCH_(3))_(2)]_(6)` is a high polymer insoluble in hydrocarbon solvents. On the other hand, tertiary - butoxy derivative is less condensed being only a trimer `[Be(O-t-Bu)_(2)]_(3)`
With bulky alkoxide groups the beryllium compound exists as monomers which have

A

Linear structure with `180^(@)` bond angle

B

Trigonal planar structure with `120^(@)` bond angle

C

Tetrahedral structure with `190^(@)28^(3)` bond angle

D

Distorted tetrahedral structure with more than `109^(@)28^(1)` in interal C - Be - C bond

Text Solution

Verified by Experts

The correct Answer is:
A
Beryllium compounds which exists as monomers have linear structures with bond angle `180^(@)C`
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Alkoxides of beryllium [Be(OR)_(2)]_(6) usually have associated strutures with both mu_(2) - bridging and terminal OR groups. For example [Be(OCH_(3))_(2)]_(6) is a high polymer insoluble in hydrocarbon solvents. On the other hand, tertiary - butoxy derivative is less condensed being only a trimer [Be(O-t-Bu)_(2)]_(3) The vapour phase, BeCI_(2) is

Alkoxides of beryllium [Be(OR)_(2)]_(6) usually have associated strutures with both mu_(2) - bridging and terminal OR groups. For example [Be(OCH_(3))_(2)]_(6) is a high polymer insoluble in hydrocarbon solvents. On the other hand, tertiary - butoxy derivative is less condensed being only a trimer [Be(O-t-Bu)_(2)]_(3) The C - Be - C angle [Be(CH_(3))_(2)]_(n) is

Hydrogen bonding is said to be formed, -when sightly acidic hydrogen-atom attached to a strongly, electronegative fluorine, oxygen or nitrogen atom. is held with weak. electrostatic forces by the non-bonded pair of electrons of another atom. The co-ordination number of hydrogen in such cases is two. It acts as a bridge between two atoms, to one of which it is covalently bonded and to other attached through electrostatic forces, also called hydrogen bond. Though the hydrogen atoms in a methyl group are not polarised, if an electronegative group like chloro, carbonyl, nitro or cyano (in order to increase electronegativity) is attached to it, the C-H bond gets polarised due to the inductive effect and the hydrogen atom becomes slightly acidic resulting in the formation of weak hydrogen bonds. Though a weak bond the H-bond effects is large number of the physical properties of compounds some of which are - Boiling points of liquids - Solubility of polar compounds in polar solvents (containig H attached with strong electronegative atom) - Viscosity of liquids . Acidity Which of the following combinations can involve hydrogen bonding I) Mixture of KF and HF " " II) Mixture of CH_(3)COCH_(3) and CHCI_(3) III) Mixture of NH_(4) CI and H_(2)O" " IV) Mixture of CH_(3) and H_(2)O

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 ?

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Numerous forms of the periodic table have been devised from time to time. A modern version which is most convenient and widely used is the long or extended from of periodic table. The aufbau principle and the electronic configuration of atoms provide a theoretical foundation for the periodic classification. The horizontal rows are called periods. There are altogether seven periods. The first period consists of 2 elements. The subsequent periods consists of 8, 8,18, 18 and 32 elements respectively. The seventh period is incomplete and like the sixth period would have maximum of 32 elements. Elements having similar outer electronic configurations in their atoms are grouped in vertical columns. These are referred to as groups or families. According to the recommendations of IUPAC, the groups are numbered 1 to 18 replacing the older notation of groups 0, IA, IIA, ....VIIA, VIII, IB.....VIIB. Each successive period in the periodic table is associated with the filling up next higher principal energy level following aufbau sequence. The number of elements in each period is twice the number of atomic orbitals available in the energy level that is being filled. All the elements are classified into four blocks, i.e., s-block, p-block, d-block, and f-block depending on the type of atomic orbitals that are being filled with electrons. Elements A, B, C, D and E have the following electronic configuration: (A) 1s^2, 2s^2 2p^1 (B) 1s^2, 2s^2 2p^6 , 3s^2 3p^1 (C ) 1s^2, 2s^2 2p^6 , 3s^2 3p^3 (D) 1s^2 , 2s^2 2p^6 , 3s^2 3p^5 (E) 1s^2 , 2s^2 2p^6 , 3s^2 3p^6 Which among these will belong to same group in the periodic table ?

Passage-IV : Sulphur and rest of the elements of group 16 are less electronegative than oxygen. Therefore, their atoms cannot take up electrons easily. They can acquire ns^(2)np^(6) configuration by sharing two electrons with the atoms of other elements and thus, exhibit +2 oxidation state in their compounds. In addition to this, their atoms have vacant d-orbitals in their valence shell to which electrons can be promoted from the p and s-orbitals of the shell. As a result, they can show +4 and +6 oxidation states shell. The nature of the compounds of sulphur having +4 oxidation state is :

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