Answer:
Multiply the wavelength by the frequency.
Explanation:
The velocity of a wave is the frequency times the wavelength.
Answer:
The answer is a," their receptors are sensitive to chemical molecules."
Answer:
The electric force between them if the pieces of grain are 2 cm apart is
.
Explanation:
Given:
Charge on one grain, 
Charge on another grain, 
Separation between them, 
Electric force acting between two charges
separated by a distance
is given as:

Where,
is Coulomb's constant equal to
.
Now, plug in all the values and solve for
.

Therefore, the electric force between them if the pieces of grain are 2 cm apart is
.
Accrording to me Mg should be that element because <span>Magnesium forms divalent cations and is capable of accepting 2 anions such as Fluorine</span>