Answer is: the energy of exactly one photon of this light is 4.75·10⁻¹⁹ J.
Photon energy equation: E = h·ν.
E - energy of one photon.
ν- frequency.
h - Planck's constant.
ν = 7.17·10¹⁴ Hz.
h = 6.63·10⁻³⁴ J·s.
E = 6.63·10⁻³⁴ J·s · 7.17·10¹⁴ Hz.
E = 4.75·10⁻¹⁹ J.
B.. it is a combination reaction... A + B--> AB
Answer:
No, because Flourine can only form 1 bond, thus backbonding is not obtainable
Answer:
In the option(A) moles of HCl left are 0.100 moles which is wrong, making the option incorrect.
Explanation:

Moles of HCl = n
Molarity of HCl = 1.0M
Volume of HCl solution = 30.0 mL = 0.030 L (1 mL = 0.001L)


Moles of Fe = 
According to recation , 1mol of Fe reacts with 2 mol HCl. Then 0.01 mole of Fe will recat with :
of HCl
This means that HCl uis in excess , hence excessive reagent.
Moles of HCl left unreacted :
= 0.030 mol - 0.020 mol = 0.010 mol
But in the option moles of HCl left are 0.100 moles which is wrong, making the option incorrect.
This can be, for example, halogensubstituted hydrocarbons.
CCl₄, C₂F₆.
Or halides halocarboxylic acids, and other compounds.
O
II
Cl₃C-Cl