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प्रश्न
What are alloys?
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उत्तर
An alloy is a blend of metals prepared by mixing the components. Alloys may be homogeneous solid solutions in which the atoms of one metal are distributed randomly among the atoms of the other.
संबंधित प्रश्न
Which metal in the first transition series (3d series) exhibits + 1 oxidation state most frequently and why?
What are the transition elements? Write two characteristics of the transition elements.
Which is a stronger reducing agent, Cr2+ or Fe2+ and why?
Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?
How would you account for the following:
Of the d4 species, Cr2+ is strongly reducing while manganese (III) is strongly oxidising.
Calculate the number of unpaired electrons in the following gaseous ions:
Mn3+, Cr3+, V3+ and Ti3+. Which one of these is the most stable in an aqueous solution?
Give reasons: Sc3+ is colourless in aqueous solution whereas Ti3+ is coloured.
Transition metals with lowest melting point is ______.
Electronic configuration of Mn2+ is ____________.
Read the passage given below and answer the following question:
The transition metals when exposed to oxygen at low and intermediate temperatures form thin, protective oxide films of up to some thousands of Angstroms in thickness. Transition metal oxides lie between the extremes of ionic and covalent binary compounds formed by elements from the left or right side of the periodic table. They range from metallic to semiconducting and deviate by both large and small degrees from stoichiometry. Since electron bonding levels are involved, the cations exist in various valence states and hence give rise to a large number of oxides. The crystal structures are often classified by considering a cubic or hexagonal close-packed lattice of one set of ions with the other set of ions filling the octahedral or tetrahedral interstices. The actual oxide structures, however, generally show departures from such regular arrays due in part to distortions caused by packing of ions of different size and to ligand field effects. These distortions depend not only on the number of d-electrons but also on the valence and the position of the transition metal in a period or group.
In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage.
Assertion: Cations of transition elements occur in various valence states.
Reason: Large number of oxides of transition elements are possible.
When a brown compound of manganese (A) is treated with \[\ce{HCl}\] it gives a gas (B). The gas taken in excess, reacts with \[\ce{NH3}\] to give an explosive compound (C). Identify compounds A, B and C.
Account for the following:
In case of transition elements, ions of the same charge in a given series show progressive decrease in radius with increasing atomic number.
Why are fluorides of transition metals more stable in their higher oxidation state as compared to the lower oxidation state?
Which of the following statements is not correct?
On adding NaOH, solution to the aqueous solution of K2CrO7 the colour of the solution changes from
Give reason for the following statement:
[Ti(H2O)]3+ is coloured while [Sc(H2O)6]3+ is colourless.
Which of the following ions acts as a typical transition metal ion?
Account for the following:
Sc3+ is colourless whereas Ti3+ is coloured in an aqueous solution.
The E° value for the Mn2+/Mn2+ couple is more positive than that of Cr3+/Cr2+ or Fe3+/Fe2+ due to the change of:
‘Spin only’ magnetic moment is the same for which of the following ions?
- Ti3+
- Cr2+
- Mn2+
- Fe2+
- Sc3+
Choose the most appropriate answer from the options given below:
