Which of the following factors can lead to desertification in the presence of natural drought?
a. deforestation
b. sustainable grazing
c. underground mining
d. all of the above

Answer : Option A) Deforestation.

Explanation : Factors related to deforestation can lead to desertification in presence of natural drought.

As natural drought hit area is an area which has low amount of water supply in the land. It is also called as below average precipitation land when drought area is deforested it will lead to desertification. As the plants in the drought area are the reason why their is at least low water is found, if these vegetation is deforested then it will lose its capacity to hold water and the land will be deserted.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2