Conduction, because there is a direct transfer of heat.
When the iron touches the fabric, the heat from the iron gets transferred to the fabric and this is why it is a conduction type of heat transfer.
D.
A more accurate answer would be -50 m/s. 50 m/s is the change in speed.
Answer : The energy for vacancy formation in silver is, 
Explanation :
Formula used :

or,

So,
![N_v=[\frac{N_A\times \rho}{M}]\times e^{(\frac{-E}{K\times T})}](https://tex.z-dn.net/?f=N_v%3D%5B%5Cfrac%7BN_A%5Ctimes%20%5Crho%7D%7BM%7D%5D%5Ctimes%20e%5E%7B%28%5Cfrac%7B-E%7D%7BK%5Ctimes%20T%7D%29%7D)
where,
= equilibrium number of vacancies = 
E = energy = ?
M = atomic weight = 107.9 g/mole
= Avogadro's number = 
= density = 
T = temperature = 
K = Boltzmann constant = 
Now put all the given values in the above formula, we get:
![3.6\times 10^{20}L^{-1}=[\frac{(6.022\times 10^{23}mol^{-1})\times 9500g/L}{107.9g/mol}]\times e^{[\frac{-E}{(1.38\times 10^{-23}J/K)\times 1073K}]}](https://tex.z-dn.net/?f=3.6%5Ctimes%2010%5E%7B20%7DL%5E%7B-1%7D%3D%5B%5Cfrac%7B%286.022%5Ctimes%2010%5E%7B23%7Dmol%5E%7B-1%7D%29%5Ctimes%209500g%2FL%7D%7B107.9g%2Fmol%7D%5D%5Ctimes%20e%5E%7B%5B%5Cfrac%7B-E%7D%7B%281.38%5Ctimes%2010%5E%7B-23%7DJ%2FK%29%5Ctimes%201073K%7D%5D%7D)

Therefore, the energy for vacancy formation in silver is, 
(3) HF. The strength of hydrogen bonding between molecules depends on the difference in the electronegativities of each atom in the molecule. Since fluorine is the most electronegative element, HF has the strongest hydrogen bonding.
Since there is no weight, I would assume that this is a 100g of pure compound.
Okay so I would be changing the percentage to gram to solve for the mole.
So
40.0g C (1 mol C/12.01 g C) = 3.33 mol C
6.73g H (1 mol H/1.01 g H ) = 6.66 mol H
53.3g O (1 mol O/16.00 g O) = 3.33 mol O
With that, two of our moles is 3.33, so we consider that are our 1, as it is also the lowest. Therefore the empirical formula is CH2O