 next property write down electronegativity what about electronegativity we know as we go down the group electronegativity decreases write down as we go down the group electronegativity decreases there is no exceptions into this okay write down next melting point and boiling point setting point boiling point write down into this melting point of the elements of group 15 increases from nitrogen to arsenic and then decreases and then decreases the melting point of the elements of group 15 first increases from nitrogen to arsenic and then decreases to antimony and bismuth the overall order is this for melting point the overall order is not a regular trend so obviously this you have to memorize nitrogen is minimum and then phosphorous bismuth then antimony and arsenic the reason behind this you write down as the atomic size increases melting point increases as the atomic size increases melting point increases the decrease in melting point the decrease in melting point of antimony and bismuth is because of inert pair effect is because of inert pair effect due to inert pair effect these elements means antimony and bismuth has tendency to form 3 covalent bond instead of 5 covalent bond 3 covalent bond instead of 5 covalent bond and we know what number of covalent bond increases melting point increases so in the case of antimony and bismuth inert pair effect is applied there what is inert pair effect you see if I write down suppose this outer most electronic configuration suppose we have 4s2 and 4p3 or suppose I am taking 5s2 5p3 5s2 5p3 so inert shell electrons inert shell you see here in 4s2 4p3 and 5s2 5p3 the inert shell will take here 6 and 6 ok because 2 3 4 5 and 6 correct so it will take 6 and 5 right again 6s2 6p3 now the inert shell electron you see 6s2 6p3 before this there is 3d and 4d electrons basically d and f orbitals present in the inert shell in both molecules you see d and f sub shell d and f sub shell shows weak screening effect d and f sub shell shows weak screening effect now because of weak screening effect these electrons the 2 electrons which is present in the s sub shell of the outer most shell which is this s sub shell of the outer most shell s sub shell of the outer most shell ॐू। ौ,। ौ,। ौ,। ौ,। ौ,। पूconnect from more metallic nature increases the elements we have nitrogen through our Islamic undermine any infantee this one in all these five elements these two the first two are non metals their properties close to note दी tears minus the range of the oxidation is that it can be anything from minus 3 to plus 5 that is one thing minus 3 to plus 5 okay okay now if you talk about the stability of plus 5 oxidation stage as we go down the group okay we know because of inert there are effect here only we have discussed that these two electrons are what these two electrons are through a bonding okay that's why a tendency to form plus 5 oxidation state as we go down the group increases or decreases decreases right right down the tendency to form plus 5 oxidation state down the group as we go down the group decreases reason is same inert sphere effect and tendency to form next line plus 3 oxidation state increases as we go down the group see minus 3 and plus 5 are the two extremes actually all these no i'm that's what i'm discussing you know minus 3 and plus 5 are two extreme conditions minus 3 when possible टाडेंे आचादा चिन्यम या काचदा चोल Jen छोर अग्छाह ज़ा औँ खिलगाई आप सपूश आप पाश़ में आप सपूश आप पुश्वाद आप सपुश call वो क्यवाँ बीद को वो पाशक़ से ती नेगवाँ इसे वहँाँ वाँ व Бог आई. वहँाँ, वहँाँ वआँ कि आट वो आप पर है। च्टी कि बी व्नेग वियत बावी ती वेः, जे वो विक्डिक वी द向आई, Otherwise,god 所以 you have to understand but as far as the preparation is concerned you have to memorize that right then you have don't have to do anything into it.