Given the law of conservation of energy, what happens when a 200°c iron bar is placed in thermal contact with a 30°c block of wood? a. energy leaves the iron bar and enters the wood until the temperatures are equal. b. energy leaves the wood and enters the iron bar until the temperatures are equal. c. all the energy from the iron bar is transferred to the wood. d. all the energy from the wood is transferred to the iron bar.

The correct option is A.

Explanation: Law of conservation of energy states that the energy cannot be lost or formed but it can only be transformed from one form to another.

Thermal energy is defined as the energy which comes from heat.

Heat flow is defined as the amount of heat transferred from the object having higher temperature to the object having lower temperature when two objects are kept in contact. As the energy remains conserved, the heat flow will take place until the equilibrium between the temperatures of two objects are achieved.

We are given that iron bar which is at 200°C is kept in contact with a block of wood which is at 30°C. The block of wood is at lower temperature than iron bar. Hence, heat will flow from the iron bar to the block of wood until the temperatures of both are equal.

Therefore, the correct option is A.

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explanation:

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