Answer:
Helium is in the __1__ period. All elements in this period have __8__ shells around the nucleus. Also giving brainiest :)
False .... A neutral atom needs the same number of protons and electrons
Answer:
Electron gain enthalpy becomes more and more negative from left to right in a period. As we move across a period from left to right the atomic size decreases and the nuclear charge increases
<u>Answer:</u> The value of
for the chemical equation is 
<u>Explanation:</u>
For the given chemical equation:

To calculate the
for given value of Gibbs free energy, we use the relation:

where,
= Gibbs free energy = 78 kJ/mol = 78000 J/mol (Conversion factor: 1kJ = 1000J)
R = Gas constant = 
T = temperature = 1000 K
= equilibrium constant in terms of partial pressure = ?
Putting values in above equation, we get:

Hence, the value of
for the chemical equation is 