Download App

The d & f Block Elements — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryThe d & f Block Elements5 Marks
Question
  1. Complete the following equations:
  1. $\text{Cr}_{2}\text{O}_{7}^{2-}+\text{2OH}^{-}\rightarrow$
  2. $\text{MnO}_{4}^{-}+\text{4H}^{+}+\text{3e}^{-}\rightarrow$
  1. Account for the following:
  1. Zn is not considered as a transition element.
  2. Transition metals form a large number of complexes.
  3. The $E ^{\circ}$ value for the $Mn ^{3+} / Mn ^{2+}$ couple is much more positive than that for $Cr ^{3+} / Cr ^{2+}$ couple.
✓

Answer

  1.  
  1. $\text{Cr}_{2}\text{O}_{7}^{2-}+\text{2OH}^{-}\rightarrow\text{2CrO}_{4}^{2-}+\text{H}_{2}\text{O}$
  2. $\text{MnO}_{4}^{-}+\text{4H}^{+}+\text{3e}^{-}\rightarrow\text{MnO}_{2}+\text{2H}_{2}\text{O}$
  1.  
  1. $Zn/Zn^{2+}$ has fully filled d orbitals.
  2. This is due to smaller ionic sizes/higher ionic charge and availability of d orbitals.
  3. because $Mn ^{+2}$ is more stable $\left(3 d^5\right)$ than $Mn ^{3+}\left(3 d^4\right) . Cr ^{+3}$ is more stable due to $t _2 g^3 / d ^3$ configuration.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "5 Marks Questions" from The d & f Block Elements→The d & f Block Elements — all question types→Chemistry STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

Match the compounds given in Column I with the oxidation state of cobalt present in it (given in Column II) and assign the correct code.
 
Column I (Compound)
 
Column II (Oxidation state of Co)
$a.$
$[Co(NCS)(NH_3)_5](SO_3)$
$1.$
$+4$
$b.$
$[Co(NH_3)_4Cl_2]SO_4$
$2.$
$0$
$c.$
$Na_4[Co(S_2O_3)_3]$
$3.$
$+1$
$d.$
$[Co_2(CO)_8]$
$4.$
$+2$
 
 
$5.$
$+3$
Code:
  1. $A (1), B (2), C (4), D (5).$
  2. $A (4), B (3), C (2), D (1).$
  3. $A (5), B (1), C (4), D (2).$
  4. $A (4), B (1), C (2), D (3).$
→
How are carboxylic acids prepared from the following compounds? Explain with examples:
(a) Primary alcohol
(b) Acyl halide
(c) Acid anhydride
(d) Grignard reagent
(e) Alkyl benzene.
→
Mr. Roy, the principal of one reputed school organised a seminar in which he invited parents and principals to discuss the serious issue of diabetes and depression in students.They all resolved this issue by strictly banning the junk food in schools and to introduce healthy snacks and drinks like soup, lassi, milk etc. in school canteens. They also decided to make compulsory half an hour physical activities for the students in the morning assembly daily. After six months, Mr. Roy conducted the health survey in most of the schools and discovered a tremendous improvement in the health of students.

After reading the above passage, answer the following:
  1. What are the values (at least two) displayed by Mr. Roy?
  2. As a student, how can you spread awareness about this issue?
  3. What are tranquillizers? Give an example.
  4. Why is use of aspartame limited to cold foods and drinks?
→
Answer the following question:
0.6mL of acetic acid $(CH_3COOH)$, having density $1.06g mL^{-1}$​​​​​​​, is dissolved in $1$ litre of water. The depression in freezing point observed for this strength of acid was $0.0205^\circ C$. Calculate the van’t Hoff factor and the dissociation constant of acid.
→
Answer the following questions:
Give reasons:
  1. d-block elements exhibit more oxidation states than f-block elements.
  2. Orange solution of potassium dichromate turns yellow on adding sodium hydroxide to it.
  3. Zirconium (Z = 40) and Hafnium (Z = 72) have almost similar atomic radii.
→
Discuss biological and industrial importance of osmosis.
→
Account for the following: Give the formula and describe the structure of a noble gas species which is isostructural with $\text{IBr}^-_2.$
→
Derive formula for degree of dissociation and degree of condensation of the solute in the solvent.
→
Write the chemical reactions of $C _2 H _5 OH$ with following compounds :
(i) $CH _2 N_2$ (diazomethane) (ii) ketone, (iii) $HC \equiv$ $C H$ (iv) $C H _3 N C O$ (Methyl-isocyanate) (v) $C H _3 C H O$ (ethanol) (vi) conc. $H _2 SO _4$ at $0^{\circ} C$.
→
Write the $" \text{IUPAC}"$ names of the following coordination compounds:
$a. \left[ Pt \left( NH _3\right)_2 Cl \left( NO _2\right]\right.$
$b. K _3\left[ Cr \left( C _2 O _4\right)_3\right]$
$c. \left[ CoCl _2( en )_2\right] Cl$
$d. \left[ Co \left( NH _3\right)_5\left( CO _3\right)\right] Cl$
$e. Hg \left[ Co ( SCN )_4\right]$
→