Nitish

For 6-8 class there is a need to study MAT type mathematical question,which inhances student thinking ability. For science no need of tutor school study is sufficient, in science things are like history, so you have to remember. So with a little help student can do.

so for 6-8 class, student must focus on MAT.

• Rationalise the given statements and give chemical reactions:
• Lead (II) chloride reacts with Cl₂  to give PbCl₄ .
• Lead (IV) chloride is highly unstable towards heat.
• Lead is known not to form an iodide Pbl₄.

Answer is explained on the basis of inert pair effect.

this is observed in p-block, on movind down the group in p-block because of poor sheilding of d & f electrons in inner shells of element ns2 electrons strongly attracted by nucleus and do not participate in chemical reaction and so

Pb2+ is more stable than Pb4+

If two allotropes of same element has different structure.it means they have different force of attraction between their molecules and different bonding tendency, which results in different physical properties. Example : diamond and graphite one has three dimensional cross linked structure while other has layered structure.diamond is hard while graphite is soft