Questions

When atoms react they do so in order to reach the lowest energy, which is the most stable. The electrons orbitals will overlap in the way that reduces the energy the most. Orbitals of similar energy will produce the greatest stabilisation.The answer you gave isn't the whole story, it depends what species is reacting with what. The effective nuclear charge on the atom will affect the energy of the valance electrons.

Hence, the reactivity of an atom arises from the existence of unpaired electrons in the valence shell.

A resource is a source or supply from which a benefit is produced. Resources can be broadly classified upon their availability they are renewable and non renewable resources.

Renewable Resources :: A resource that can be replenished after use are known as Renewable resources.

Examples :: Sunlight, Water, biomass,...

Non renewable Resources :: A resource that, once used, is no longer available are known as Non renewable Resources. 

Example :: Coal, fossil fuels, natural gas,...

Sunlight is the both renewable and inexpensive resource from the given options.

Fixed expenses are those expenses that do not change when there is a change in production or sales level.

Examples of Fixed Expenses are rent, insurance, payment on loans, salaries, advertising, etc...

Except pineapple remaining all three are types of apples.

Pineapple is what kind of apple isn't an apple.

Khan Abdul Ghaffar Khan

Second ozone hole was detected over Tibet in the year 2006. 

Ozone is a form of oxygen, acts as a high-altitude atmospheric screen against cancer-causing ultraviolet light.

The main source of these halogens in the stratosphere is photodissociation of man made halocarbon refrigerants, solvents, propellants and CFC's.