\(K_2Cr_2O_7\) paper acidified with dil. \(H_2SO_4\) turns green when exposed to :
Show Hint
The reduction of \(K_2Cr_2O_7\) by SO2 produces Cr3+ ions, which impart a green colour to the solution.
Sulphur dioxide
Sulphur trioxide
Carbon dioxide
Hydrogen sulphide
The Correct Option is A
Solution and Explanation
When \(K_2Cr_2O_7\) is acidified with dilute \(H_2SO_4 \)and exposed to\( SO_2\), it gets reduced, turning green due to the formation of\( Cr^3+\) ions:
\(Cr_2O ^{2−} _7 + 3SO_2 + 2H ^+ → 2Cr^{3+} + 3SO^{2−}_ 4 + H_2O\).
Top Questions on d block elements
- Calculate the number of unpaired electrons in [Mn(H2O)6]²⁺, considering H2O as a weak field ligand. (Atomic number of Mn = 25)
- BCECE - 2025
- Chemistry
- d block elements
- Which of the following oxides will be the most basic: Ti (22), V (23), Cr (24), Fe (26)?
- BCECE - 2025
- Chemistry
- d block elements
- The main constituents of stainless steel are:
- BCECE - 2025
- Chemistry
- d block elements
- This oxide is most basic. [Ti=22, V=23, Cr=24, Fe=26]
- BCECE - 2025
- Chemistry
- d block elements
- Which one of the following statements is not correct?
- AP EAPCET - 2025
- Chemistry
- d block elements
Questions Asked in JEE Main exam
- Let \( P_n = \alpha^n + \beta^n \), \( P_{10} = 123 \), \( P_9 = 76 \), \( P_8 = 47 \), and \( P_1 = 1 \). The quadratic equation whose roots are \( \frac{1}{\alpha} \) and \( \frac{1}{\beta} \) is:
- JEE Main - 2025
- Sequences and Series
- The value of \( (\sin 70^\circ)(\cot 10^\circ \cot 70^\circ - 1) \) is:
- JEE Main - 2025
- Trigonometric Identities
Let $ P_n = \alpha^n + \beta^n $, $ n \in \mathbb{N} $. If $ P_{10} = 123,\ P_9 = 76,\ P_8 = 47 $ and $ P_1 = 1 $, then the quadratic equation having roots $ \alpha $ and $ \frac{1}{\beta} $ is:
- JEE Main - 2025
- Relations and functions
- Let \( f(x) = \frac{x - 5}{x^2 - 3x + 2} \). If the range of \( f(x) \) is \( (-\infty, \alpha) \cup (\beta, \infty) \), then \( \alpha^2 + \beta^2 \) equals to.
- JEE Main - 2025
- Functions
- A force of 49 N acts tangentially at the highest point of a sphere (solid of mass 20 kg) kept on a rough horizontal plane. If the sphere rolls without slipping, then the acceleration of the center of the sphere is:
- JEE Main - 2025
- Quantum Mechanics
Concepts Used:
d block elements
The elements, in the columns of the periodic table in which d subshells are being occupied are known as d block elements.
These are the elements that have the capability of forming stable cations with incompletely filled d orbitals. Elements like mercury and Zinc are not considered transition metals because they have electronic configurations: (n-1)d10 ns2. These elements have filled d-orbitals in their ground state and, therefore, even in some of their oxidation states.
General Properties Of d-Block Elements
- Multiple oxidation states- The oxidation states of d block elements show very few energy gaps; therefore, they exhibit many oxidation states. Also, the energy difference between s and d orbital is very less. Therefore both the electrons are involved in ionic and covalent bond formation, which ultimately leads to multiple oxidation states.
- Formation of complex compounds- Ligands show a binding behaviour and can form so many stable complexes with the help of transition metals. This property is mainly due to:
- Availability of vacant d orbitals.
- Comparatively small sizes of metals.
- Hardness- Transition elements are tough and have high densities because of the presence of unpaired electrons.
- Melting and boiling points- Melting and boiling points of transition are very high. This is because of the presence of unpaired electrons and partially filled d orbitals. Because of these two things, they form strong bonds and therefore have high melting and boiling points.
- Atomic radii- The atomic and ionic radius of the transition elements decreases as we move from Group 3 to group 6. However, it remains the same between group 7 and group 10, and from group 11 to group 12 increases.
- Ionization enthalpy- The ionization enthalpies of the transition elements are generally on the greater side as compared to the S block elements