Answer: E. It decreases the value of Eact.
Explanation:
Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.
A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and more molecules convert to products.
The catalyst itself does not take part in the chemical reaction and is regenerated as such at the end.
Answer: The resulting isotope is 
Explanation:
Alpha Decay: In this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. The mass number is reduced by 4 units and atomic number is reduced by 2 units.

Beta Decay : It is a type of decay process, in which a proton gets converted to neutron and an electron. This is also known as -decay. In this the mass number remains same but the atomic number is increased by 1.

The resulting isotope is 
<u>Answer:</u> The nuclear binding energy of the given element is 
<u>Explanation:</u>
For the given element 
Number of protons = 3
Number of neutrons = (6 - 3) = 3
We are given:

M = mass of nucleus = 
![M=[(3\times 1.00728)+(3\times 1.00866)]=6.04782amu](https://tex.z-dn.net/?f=M%3D%5B%283%5Ctimes%201.00728%29%2B%283%5Ctimes%201.00866%29%5D%3D6.04782amu)
Calculating mass defect of the nucleus:
![\Delta m=M-A\\\Delta m=[6.04782-6.015126)]=0.032694amu=0.032694g/mol](https://tex.z-dn.net/?f=%5CDelta%20m%3DM-A%5C%5C%5CDelta%20m%3D%5B6.04782-6.015126%29%5D%3D0.032694amu%3D0.032694g%2Fmol)
Converting this quantity into kg/mol, we use the conversion factor:
1 kg = 1000 g
So, 
To calculate the nuclear binding energy, we use Einstein equation, which is:

where,
E = Nuclear binding energy = ? J/mol
= Mass defect = 
c = Speed of light = 
Putting values in above equation, we get:

Hence, the nuclear binding energy of the given element is 