Answer: The mass in 
atoms of zinc is 0.405 g.
Explanation:
Given: Atoms of zinc =
It is known that 1 mole of every substance contains 
atoms. So, the number of moles in given number of atoms is as follows.
As moles is the mass of a substance divided by its molar mass. So, mass of zinc (molar mass = 65.39 g/mol) is calculated as follows.
Thus, we can conclude that the mass in atoms of zinc is 0.405 g.
It has 4 valence electron, all of which are needed to bond with nearest neighbors
Activation energy is defined as the least amount of energy that is needed to be available in a chemical system with potential reactants in order to result a chemical reaction. Therefore, the correct answer would be the first option: the heat released in a reaction.
One can solve the problem by using the law of conservation of momentum. The total momentum prior to the collision must be equivalent to the total momentum after the collision, so we have:
m1v1 + m2v2 = m1v1 + m2v2
Here, m1 is 0.4 Kg that is the mass of the ball, u1 is 18 m/s that is the initial velocity of the ball, m2 is 0.2 Kg that is the mass of the bottle, and u2 is 0 that is the initial velocity of the bottle.
v1 is the final velocity of the ball, which is to be determined, and v2 is 25 m/s that is the final velocity of the bottle.
Substituting and rearranging the equation, one can find the final velocity of the ball:
v1 = m1u1 - m2v2 / m1 = (0.4 kg) (18 m/s) - (0.2 Kg) (25 m/s) / 0.4 Kg = 5.5 m/s.
