Questions

A typical giraffe neck can stretch as long as six feet, the giraffe's tongue usually measures 18-20 inches long.

Why that much long:

Giraffe's eat Acacia tree leaves. The acacia tree's tasty leaves are protected by very sharp thorns. The giraffe's long tongue allows it to reach the highest, tastiest leaves while avoiding the sharp thorns. Its tongue also features a thick, tough layer that protects it from being cut by the thorns. If a giraffe's tongue does get cut by a thorn, its extra-thick saliva has antiseptic properties that help it to heal quickly.

From the given data, 

if 60% = 45 minutes

100% =  ?

=> 45 × 100/60

= 75 min

i.e, = 1hr 15 min.

Electronegativity refers to the ability of an atom to attract shared electrons in a covalent bond. The higher the value of the electronegativity, the more strongly that element attracts the shared electrons.

Electronegativity increases from bottom to top in groups, and increases from left to right across periods. Thus, fluorine is the most electronegative element and lithium is the least.