Freeze drying<span> (or lyophilization) removes water from the ice cream by lowering the </span>air pressure<span> to a point where ice sublimates from a </span>solid<span> to a </span>gas<span>. The ice cream is placed in a </span>vacuum chamber<span> and frozen until the water </span>crystallizes<span>. The air pressure is lowered, creating a partial vacuum, forcing air out of the chamber; next heat is applied, </span>sublimating<span> the ice; finally a freezing coil traps the vaporized water. This process continues for hours, resulting in a freeze-dried ice cream slice. </span>
Answer:
Wavelength, 
Explanation:
Given that,
Frequency, 
We need to find the wavelength of a photon of light. The relation between frequency and wavelength is as follows :
So, the wavelength of the light is 
.
<h2>Answer:</h2>
The correct answer is option B which is neutron absorbing material.
<h3>Explanation:</h3>
- In nuclear reactors, uranium absorbs a neutron, broke into two nuclei and releasing 3 more neutrons and energy. These neutrons further absorbed by other uranium atoms.
- Control rods are used to control the fission reaction in nuclear reactors by absorbing neutrons.
- Hence the material used in control rods is neutron absorbing material.
Answer:
1.61 x 10²⁰ molecules
Explanation:
Given parameters:
Mass of the hydrogen gas = 8.01 x 10⁻⁴g
Unknown
Number of molecules of NH₃ = ?
Solution:
Given reaction:
N₂ + 3H₂ → 2NH₃
We have to solve from the known to the unknown
- The known specie is the mass of H₂ ;
find the number of moles of the specie;
number of moles = 
Molar mass of H₂ = 2(1) = 2g/mol
Number of moles = 
= 0.0004mol
- 3 moles of H₂ will produce 2 moles of NH₃
0.0004 moles of H₂ will produce 
= 0.00027moles of NH₃
1 mole of a substance contains 6.02 x 10²³ molecules
0.00027mole of NH₃ will contain 0.00027 x 6.02 x 10²³
= 1.61 x 10²⁰ molecules
