Question

give scientific reason , gills of doors and windows are always painted before they are used
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Answer 1

Answer

1) We know that fuse is a device that breaks the circuit when there is high current flow, this preventing other appliances. To break the circuit it has to melt and so to melt it has to have a low melting point. Say we have the metal Tungsten that's used in the filaments of bulb, which has a very high melting point then obviously the fuse won't break even when high current flows and due to this other appliances will get affected. This is why they use materials of low melting point.

2) These elements are this that have zero valence electrons. Valence electrons are those that are present in the outermost shell of an atom. Always an atom tried to fill its outermost shell to the maximum number of electrons it can hold. This is the one which decided the reactivity of the element. Inert gases already have their outermost shell full, i.e the outermost shell would have the maximum number of electron. So now there is no need for these elements to react. And so as they don't react they are called as Noble gases

Answer 2

Required Answer:-

3)$\bigstar$ Question:-

$\leadsto$Give reason that gills of doors and windows are always painted before they are used?.

$\bigstar$ Answer:-

$\leadsto$grills of doors and windows are usually made out of iron.

$\leadsto$it is sure that a piece of iwron will get rusted if contacted with water and oxygen or simply moisture to avoid this to happen,we usually paint them.

$\leadsto$the molecules present in it will prevent the iron from having a contact with moisture and hence,reduce the fact of getting rusted.

1)$\bigstar$ Question:-

$\leadsto$Give reason , that zero group elements are called noble gases?..

$\bigstar$ Answer:-

$\leadsto$Because,They form very few compounds, that's why, these are known as noble gas.