1.2*10^24# atoms of chlorine
Explanation:
Chlorine gas (#Cl_2#) has two atoms of elemental chlorine in a molecule, so:
#1# mol of #Cl_2# have #6*10^23# molecules of #Cl_2#
#1# molecule of #Cl_2# have #2# atoms per molucule
Then #2*6*10^23 = 1.2*10^24# atoms of chlorine in a mol of chlorine gas
Explanation:
a) The amount of heat released by coffee will be absorbed by aluminium spoon.
Thus, 
To calculate the amount of heat released or absorbed, we use the equation:

Also,
..........(1)
where,
q = heat absorbed or released
= mass of aluminium = 45 g
= mass of coffee = 180 g
= final temperature = ?
= temperature of aluminium = 
= temperature of coffee = 
= specific heat of aluminium = 
= specific heat of coffee= 
Putting all the values in equation 1, we get:
![45 g\times 0.80J/g^oC\times (T_{final}-24^oC)=-[180 g\times 4.186J/g^oC\times (T_{final}-83^oC)]](https://tex.z-dn.net/?f=45%20g%5Ctimes%200.80J%2Fg%5EoC%5Ctimes%20%28T_%7Bfinal%7D-24%5EoC%29%3D-%5B180%20g%5Ctimes%204.186J%2Fg%5EoC%5Ctimes%20%28T_%7Bfinal%7D-83%5EoC%29%5D)

80.30 °C is the final temperature.
b) Energy flows from higher temperature to lower temperature.Whenever two bodies with different energies and temperature come in contact. And the resulting temperature of both bodies will less then the body with high temperature and will be more then the body with lower temperature.
So, is our final temperature of both aluminium and coffee that is 80°C less than initial temperature of coffee and more than the initial temperature of the aluminum.
energy is required to move from one state or phase of matter to the next. Energy is used to make a liquid into a gas or a solid into a liquid.
Mineral because its not a rock
substance is matter of particular or definite chemical constitution ex: iron, methane
mixture are two or more substances that have been combined to retain their individual chemical characteristics ex: salt water, cola