Download App

Question Bank [2022] — Chemistry STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceChemistryQuestion Bank [2022]4 Marks
Question
Write two applications of lanthanoids.
✓

Answer

  1. The lanthanoid compounds are present in every household. It is inside the colour television tubes. When electrons are bombarded on certain mixed lanthanoid compounds, they emit visible light over a small wavelength range. Therefore, the inside surface of a television tube or computer monitor is coated with tiny patches of three different lanthanoid compositions to give three colours that make the colour image.
    For example, a mixed oxide of europium and yttrium $(Eu, Y)_2O_3$ releases an intense red colour when bombarded with high energy electrons.
  2. The optoelectronics applications use lanthanoid ions as active ions in luminescent materials. The most notable application is the Nd: YAG laser (Nd: YAG = neodymium-doped yttrium aluminium garnet).
  3. Erbium-doped fibre amplifiers are significant devices in optical fibre communication systems.
  4. Lanthanoids are used in hybrid cars, superconductors and permanent magnets.

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 "Answer the following in detail." from Question Bank [2022]→Question Bank [2022] — all question types→Chemistry STD 12 Science question papers→Maharashtra Board STD 12 Science question papers→Maharashtra Board question paper generator→

Similar questions

Classify the following into intensive and extensive properties.

Pressure, volume, mass, temperature.

→
Write the electronic configuration of chromium and copper.
→
Answer the following
Define the following term: Nanotechnology
→
What is effect of temperature on solubility of solids in water? Give examples.
→
Answer in brief.How much heat is evolved when $12\ g$ of $CO$ reacts with $NO_2$​​​​​​​? The reaction is:
$4CO_{(g)} 2NO_{2(g)} \rightarrow 4CO_{2(g)} + N_{2(g)}, \triangle _rH^\circ = - 1200 kJ$
→
Define and explain different types of processes.
→
Explain the structure of carbonyl functional group.
→
What is dehydrohalogenation? State the rule for the formation of the preferred product of dehydrohalogenation.
→
An organic compound 'A' having molecular formula $C _4 H _{10} O$ does not react with sodium metal. On hydrolysis with dilute $H _2 SO _4$ it gives only one organic compound ' $B$ ' The compound $B$ on heating with red phosphorus and iodine gives compound ' $C$ '. The compound $C$ can also be obtained from compound 'A' on heating with excess HI. Identify the compounds $A , B$ and $C$.
→
The first ionisation enthalpies of S, Cl and Ar are $1000, 1256$ and $1520$ kJ/mol-1, respectively. Explain the observed trend.
→