<span>The message that a neuron carries is the nerve. This gives a signal and acts as a nerve. </span>
The energy required to break existing chemical bonds in reactants is called the activation energy.
<h3>What is activation energy?</h3>
Activation energy in chemistry is the energy required to initiate a chemical reaction.
Chemical reactions involve the breaking of chemical bonds in substances called reactants to form new substances called products.
The energy required to break the bond in the existing reactants thus elevating these substances to a state of high activation is known as activation energy.
Therefore, it can be said that energy required to break existing chemical bonds in reactants is called the activation energy.
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Answer : The correct option is, 0.21 moles
Solution : Given,
Molarity of the solution = 0.85 M = 0.85 mole/L
Volume of solution = 250 ml = 0.25 L 
Molarity : It is defined as the number of moles of solute present in one liter of the solution.
Formula used :

Now put all the given values in this formula, we get the moles of solute of the solution.


Therefore, the moles of solute is, 0.21 moles
Answer: option D is right.
Explanation: There are four types of fundamental forces in nature.These are named as gravitational force,electromagnetic force,strong nuclear force and weak nuclear force.
As per the question we have to understand the role of strong nuclear force and weak nuclear force.
An atom consists of a nucleus surrounded by extra nuclear part consisting of electrons in various orbits.The nucleus contains two basic particles called protons and neutrons .Protons are positively charged while neutrons are neutral.Protons being positively charged will impart repulsive force on each other and may come out of the nucleus.But the nucleus is stable.That is due to the strong nuclear force.
Strong nuclear force is a spin dependent and charge independent force which comes into existence due to the mutual interaction of gluons which binds the protons and neutrons .Hence it is attractive in nature.It's 100 times more stronger than electromagnetic force also.
Weak nuclear force comes into existence during radio -active decay .This force is due to the exchange of ' w' and 'z' bosons[the particles like protons and neutrons having integral or zero spin] which are heavier in nature.The role of it is to change protons into neutrons and vice versa.Its a short range force.
Hence the option D is right.
Considering mass percentages, stars in the vicinity of the sun contain only 2% other elements by mass. Other than the main components, hydrogen and helium, stars have some heavier elements such as carbon, nitrogen, oxygen and iron. These elements are found near or in the star's core and are ejected into space when the star dies.