Formal charge can be calculated from the following formula
Formal charge = valency of central atom - (number of lone pair of electrons + number of covalent bonds)
a) for methylene:
Formal charge = 4 -( 2+ 2) = 0
b) For methyl free radical
Formal charge = 4- (3 +1) = 0
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.
Answer: C. no new substances
are formed<span>
</span><span>
<span>In the
physical change of matter, there is no new substance that is formed. It is only
the appearance of the matter that is being changed and not its chemical
composition. Cutting, tearing and grinding are only some of the examples that
exhibit physical change. </span></span>
Answer:
concave lens
Explanation:
it's concave lens because it diverges the ray/beam of light.