When a person holds an object, it has potential energy. how will the potential energy change if the person lifts the object above his or her head?
a. the object's potential energy will be zero.
b. the object's potential energy will be the same.
c. the object's potential energy will be less.
d. the object's potential energy will be greater.

D. The objects potential energy will be greater.

Explanation:

Potential energy is expressed in

PE = mgh

Where PE is the product of mass of the object, g which is acceleration to gravity and height.

PE and height is directly proportional which means that any changes in height will change the value of the PE. Increase in height means increase in PE.

it is the most commonly accepted one

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