I want to say A only... Hope I helped!!
Oxygen is needed to carry out a lot of biochemical processes in the body. If the amount of oxygen available to the blood decreases significantly a lot of things will go wrong in the body. For instance, lack of adequate oxygen will lead to the death of neurons which will eventually leads to brain cells death and irreparable brain damage. Oxygen is also needed for cellular respiration, without respiration, there will not be oxygen for carrying out various cellular activities and this will result into death. Oxygen deprivation will also leads to difficulty in breathing and other associated problems.
<u>Answer:</u> The longest wavelength of light is 656.5 nm
<u>Explanation:</u>
For the longest wavelength, the transition should be from n to n+1, where: n = lower energy level
To calculate the wavelength of light, we use Rydberg's Equation:
Where,
= Wavelength of radiation
= Rydberg's Constant = 
= Higher energy level = 
= Lower energy level = 2 (Balmer series)
Putting the values in above equation, we get:
Converting this into nanometers, we use the conversion factor:
So, 
Hence, the longest wavelength of light is 656.5 nm
Answer: Option (b) is the correct answer.
Explanation:
A solution whose constituent particles are uniformly distributed in the solution is known as a homogeneous solution.
In a homogeneous solution, particles of one solute completely dissolves in the solvent. This solution is also known a true solution.
When sand and water are mixed together then after a certain interval of time sand particles will settle at the bottom. Therefore, they do not dissolve in water. So, it is not a homogeneous solution.
When salt and water are mixed together then the salt particles will dissolve in water. Therefore, it is a homogeneous solution.
Salad dressing is not a homogeneous solution as it contains different solutions like oil, lemon juice etc which does not dissolve when mixed together.
On the other hand, soil is also not a homogeneous solution because we can visualize the distinct layers present in a soil. These layers when mixed in a solution does not dissolve so they did not form a homogeneous solution.
Thus, we can conclude that out of the given options, salt and water is a homogeneous mixture.
