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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Answer:
A. Atoms randomly crashing into each other
E. The force of one object pushing against the force of another object.
Explanation:
Forces can be classified into two categories based upon the the mode of transfer or application:
1. Contact forces
2. Non-contact forces
Contact forces are the ones which require the physical contact of the matter to get transferred and tend to create the affect. Whereas non-contact forces have the field property which transfers the affect of force from one point to another without any physical contact of the matter or the medium.
- Atoms crashing onto each other have some mass and velocity which upon collision impacts the other atoms exerts a contact force.
- The interaction between the charged particles due to their charges is always due to the electric field be it electron or proton, be it within an atom or out of an atom.
- The force between any two objects pushing or pulling each other is also possible only due to contact.
An acid is deemed strong if it can readily or easy "donate" a proton (H+) to the other ions in the solutions. Also, to donate or lose the proton or H+, the acid must dissociate (split into ions) in the solution. The more it can readily dissociate, the stronger the acid is.
Answer:
No moon has no light.
Explanation:
It only reflects the light coming from the sun. Only star produces light and moon is a satellite that revolvs around the earth.
C3H8 + 5O2 -----> 3CO2 + 4H2O
This is propane burning in air or pure oxygen.