Answer:
Mixing of salt is physical change.
Explanation:
Mixing of salt is physical change because no chemical reaction occur between them. Sand is non polar while salt is polar.
Physical Change:
The changes that occur only due to change in shape or form but their chemical or internal composition remain unchanged.
These changes were reversible.
They have same chemical property.
These changes can be observed with naked eye.
Chemical change:
The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.
These changes are irreversible
These changes occur due to chemical reactions
These may not be observed with naked eye
A) 4400 kj of heat released into surroundings
<h3>Further explanation</h3>
Reaction
C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O, the ∆H is –2200 kJ
Reaction exothermic( ∆H=-, released heat to surrounding) and for combustion of 1 mole of C3H8
So for two moles of C3H8, the enthalpy :
An example of an external stimulus is a decrease in oxygen levels in the blood during exercise.
Option C
<h3>What is stimulus?</h3>
A stimulus is defined as a thing or sensation that causes a specific reaction in an organ or tissue of a living organism
There are two types of stimuli:
- Internal stimulus
- External stimulus
Learn more about stimulus:
brainly.com/question/20117556
Ecological succession is the steady and gradual change in a species of a given area with respect to the changing environment. it is a predictable change and is an inevitable process of nature al all the biotic components have to keep up with the changes in our environment.
Answer: Option (b) is the correct.
Explanation:
It is known that energy is directly proportional to frequency.
Mathematically, 
or, E = 
............ (1)
where, E = energy
h = Plank's constant
= frequency
This relation shows that higher is the energy then more will be the frequency of electrmagnetic radiation.
Also, 
......... (2)
where, c = speed of light
= wavelength
Therefore, substituting value of from equation (2) into equation (1) as follows.
E =
E = 
This relation shows that higher is the energy then lower will be the wavelength.
Thus, we can conclude that as the energy of a photon increases, its frequency decreases, is incorrect statement.
