According to the graph, if you are in a biome where the annual precipitation is about 300 cm and the average temperature is around 25 degrees celsius, where are you?

We are in Tropical Rainforests.

Explanation:

Biome is basically an ecological region of earth that has specific type of flora and fauna (plants and animals). Every biome has specific abiotic factors like specific climate, temperature, geology, vegetation, soils and relief.

There are total 8 biomes in the world

Now in our question, we have been given some conditions and are asked to identify the biome. The annual precipitation is about 300 cm and the average temperature is around 25 degrees Celsius.

Now, if we study the characteristics of all these biomes, it is very simple to identify that the biome is Tropical Rainforest.

Important characteristics of Tropical Rainforest:

Note: You can study the characteristics of world’s other biomes in the link : http://www.physicalgeography.net/fundamentals/9k.html

Hope it helps!  :)

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.