Choose the image where a chemical reaction has not taken place eggs cooked marshmallows browned water boiled seeds grew

Answer : the correct option is, Water boiled  

Explanation :

Eggs cooked  : It is a chemical change because a new compound or substance is formed by the cooking. As we know that a liquid is present inside the egg when we are cooking egg then the liquid changes to solid.

Marshmallows browned  : It is a chemical change due to the burning of sugar. In the sugar burning process, sugar react with oxygen to give carbon dioxide and water as a product.

Water boiled  : It is not a chemical change. It is a physical change because in this process only phase changes from liquid state to gaseous state.

Seeds grew : It is a chemical change due to the process of photosynthesis in which a carbon dioxide react with water in presence of sunlight to gives glucose and oxygen as a product.

Hence, Water boiled is not a chemical change.

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