JEE 2014 :: Advanced 2014 :: Chemistry 2014

• Advanced 2014 - Physics 2014
• Advanced 2014 - Chemistry 2014
• Advanced 2014 - Mathematics 2014

The total number of distinct naturally occurring amino acids obtained by complete  acidic hydrolysis of the peptide shown below is

Answer:

Explanation:

Plan  This problem can be solved by performing hydrolysis of peptide and deciding the nature of the product.

 Chemical reaction  and product formed after hydrolysis of given peptide  can be  represented as

  (A)  is glycine which is only naturally occurring amino acid. while (B),(C) and (D)  are not the naturally occurring amino acids Hence, correct integer is (1)

 In an atom, the total number of electrons  having quantum  numbers n=4,|m_l|=1  and m_s=-1/2 is 

Answer:

Explanation:

Plan  This problem is based on concept of quantum number. Follow the following steps to solve this problem. 

Write all possible orbitals having combination of same principle, azimuthal magnetic and spin quantum number.

Then count the all possible  electrons  having given set of quantum numbers

 For n=4, the total  number of possible  orbitals are

According to question |m₁|=1, i.e, there are two possible  values of m₁, i.e, +1 and -1

 and one orbital can contain maximum two electrons one having  s=+1/2 and other having s=-1/2

 So, total number of orbitals having (|m₁|=1)=6

 Total number of electrons having (|m₁|=1  and m₂=-1/2)  =6

The correct statement(s)  for orthoboric  acid is/are

Answer:

Explanation:

(a) It does not undergo self ionisation  in water but accepts  an electron pair from water  so it behaves as a weak monobasic acid

  $H_{3}BO_{3}+H_{2}O\rightleftharpoons B(OH)_{4}^{-}+H^{+}$

 Hence, (a) is incorrect.

  (b)  When treated with 1,2 -dihydroxy or polyhydroxy compounds, they form chelate  (ring complex)  with effectively remove [B(OH)₄]^-    species from solution and thereby produce the maximum number of H₃O+ or H⁺ ions. i,e, results in increased acidity.

(c) Baric acid crystallises in a layer structure in which planar triangular BO₃^3- ions are bonded together through hydrogen bonds.

 (d)  In water the pK_a value  of H₃BO₃ is 9.25

$H_{3}BO_{3}+H_{2}O\rightleftharpoons B(OH)_{4}^{-}+H^{+}:pK_{a}=9.25$

 So, it is weak electrolyte in water

 An ideal gas in a thermally insulated vessel at internal pressure =p₁. Volume =V₁. and absolute temperature =T₁ expands irreversibly  against  zero  external pressure, as shown in the diagram.

 The final internal pressure, volume  and absolute temperature of the gas are p₂,V₂ and T₂  respectively. For this expansion

Answer:

Explanation:

Plan:This problem includes concept of isothermal adiabatic irreversible  expansion.

 Process is adiabatic  because of the use of thermal insolution therefore ,q=0

$\because   p_{ext}=0 $

$ W= p_{ext}.\triangle V  $

$=0\times \triangle V=0$

Internal energy can be written as

  $\triangle$ U=q+w=0

 The change in internal  energy of an ideal gas depends only on temperature and change in internal energy ($\triangle U$)=0 therefore , $\triangle T=0$  hence , process is isothermal and

                         T₂=T₁

 and     $ p_{2}V_{2}=p_{1}V_{1}$

 (d)   $p_{2}V_{2}^{r}=p_{1}V_{1}^{r}$ is incorrect. It is valid for adiabatic reversible  process.

 Hence, only (a) ,(b) and (c) are correct choices.

The  correct combination of names for isomeric alcohols with molecular formula C₄H₁₀O is/are

Answer:

Explanation:

Plan   This problem is based on the structure and nomenclature of organic compound. Draw structure of each compound and write IUPAC name of the given compound. Match the molecular formula of given compound with a molecular formula  of compound given in choices

  The combination  of names for possible isomeric alcohols with molecular formula C₄H₁₀O   is/are

 Hence, all choices (a), (b) and (c) are correct

• Advanced 2014 - Physics 2014
• Advanced 2014 - Chemistry 2014
• Advanced 2014 - Mathematics 2014