Answer:
Bonds are broken and new bonds are formed during chemical reactions only.
Explanation:
- A physical change in a substance doesn't change what the substance is.
- In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed.
- Physical changes can be reversed, chemical changes cannot be reversed with the substance changed back without extraordinary means, if at all. For example, a cup of water can be frozen when cooled and then can be returned to a liquid form when heated.
So, the right choice is:
Bonds are broken and new bonds are formed during chemical reactions only.
To find the number of neutrons in an atom you can use and equation
N = Mass no. - Protons
N of chlorine-36 = 36 - 17 = 19
so chlorine-36 has 19 neutrons
hope that helps
The simple trick which one can consider in such problem where it is asked for positron emission is :
<span>When the atomic number goes DOWN by one and mass number remains unchanged, then a positron is emitted.
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<span>a. </span>
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Here the atomic number decreases by one.
Similarly, options b and d are eliminated.
Option c is also not the answer.
For c, Count the atomic number on left side and compare it with right side. You will see it is 9 on left and 8 on right. Atomic no. did go down by 1. But the atomic mass is changed as well.
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