What are the answers?
in order to get help i would need the answers :)
By definition we have to:
LOG (k2 / k1)=(-Ea/R)*(1/T1-1/T2)
Where,
k1 = 0.0117 s-1
K2 = 0.689 s-1
T1 = 400.0 k
T2 = 450.0 k
R is the ideal gas constant
R = 8.314 KJ / (Kmol * K)
Substituting
ln (0.0117/0.689)=-Ea/(8.314)*((1/400)-(1/450))
Clearing Ea:
Ea = 122 kJ
answer
<span> the activation energy in kilojoules for this reaction is
</span> Ea = 122 kJ
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<u>Answer:</u> The velocity of released alpha particle is 
<u>Explanation:</u>
According to law of conservation of momentum, momentum can neither be created nor be destroyed until and unless, an external force is applied.
For a system:

where,
= Initial mass and velocity
= Final mass and velocity
We are given:

Putting values in above equation, we get:

Hence, the velocity of released alpha particle is 
Answer: In all cases, gravitational potential energy, respect from a common reference level (street level for instance) is the same.
Explanation:
Gravitational potential energy, comes from the action of the gravitational field, which is a conservative one.
This means, that if someone does work against the field (for instance lifting a weight from the ground to a given height), and then drops the weight, the work done by the field will be exactly the same.
Otherwise, the object would have remaining energy after returning to the starting point, which would violate the laws of physics, specially Thermodynamic's 2nd Law.
For this reason, the gravitational potential energy only depends from the height, and is independent from the path taken to reach there.