B, c, o, f, and n are p-block elements. what is the correct order of reactivity of these elements (from greatest to least)?

The order of reactivity will be F > O > N > C > B.

Explanation:

Reactivity of an element is defined as the tendency for it to gain or loose electrons easily.

From the given elements, all are non-metals except boron.

Boron is a metalloid and it does not attract or loose electrons easily. Hence, it is the least reactive element.

Reactivity of non-metals increases across a period because of the decrease in size and electrons are more attracted towards the nucleus and hence, can gain electrons easily. Therefore, the most reactive metal will be fluorine.

Hence, the order of reactivity will be F > O > N > C > B.

Explanation:

Heat lost by metal = mass x specific heat x fall in temperature

= 74 x S x ( 94 - 32 )

= 4588 S

heat gained by water = mass x specific heat x rise in temperature

= 120 x 1 x ( 32 - 26.5 )   ( specific heat of water is 1 cals / gm )

= 660

Heat lost = heat gained

4588S = 660

S = .14 cal /gm .

Specific heat of metal = .14 cal  / gm