Answer :
(a) The energy of blue light (in eV) is 2.77 eV
(b) The wavelength of blue light is 
Explanation:
The relation between the energy and frequency is:

where,
h = Plank's constant = 
Given :
Frequency = 
Conversion used :

So,


Also,

So,


The energy of blue light (in eV) is 2.77 eV
The relation between frequency and wavelength is shown below as:

Where,
c = the speed of light = 
Frequency = 
So, Wavelength is:


Conversion used : 
The wavelength of blue light is 
Answer:
5,844 grams of NaCl
Explanation:
Knowing the molecular weight 58,44 g/mole and saying 1 molar solution is 58,44 of NaCl in 1 liter of solution. 100 mL means 10% of the whole solution then we are going to have 10% of NaCl
58,44 x 0,1 = 5,844 grams of NaCl
Empirical formula: The formula consist of proportions of the elements which is present in the compound or the simplest whole number ratios of atoms.
Now, molecular formula is equal to the product of n (ratio) and empirical formula.
Molecular formula =
(1)
molecular formula =
(given)
Since, 6 is the smallest subscript in above molecular formula to get the simpler whole number of atoms. Therefore, divide all the subscripts i.e. number of carbon atoms (12), number of hydrogen atoms (24) and number of oxygen atoms (6) by 6.
empirical formula becomes 
Thus, according to the formula (1)
Hence, empirical formula of given molecular formula is 
Answer: 15062.4 Joules
Explanation:
The quantity of heat energy (Q) required to heat a substance depends on its Mass (M), specific heat capacity (C) and change in temperature (Φ)
Thus, Q = MCΦ
Since,
Q = ?
Mass of food = 200.0g
C = 4.184 j/g°C
Φ = (Final temperature - Initial temperature)
= 83.0°C - 65.0°C = 18°C
Then, Q = MCΦ
Q = 200.0g x 4.184 j/g°C x 18°C
Q = 15062.4 J
Thus, 15062.4 joules of heat energy was contained in the food.