a is the correct answer .
2.4 × 10^24
Answer:
B. Na+ and O2-
Explanation:
Na+ plus has 10 electrons and O2- also has 10 electrons
Answer : The pressure in the flask after reaction complete is, 2.4 atm
Explanation :
To calculate the pressure in the flask after reaction is complete we are using ideal gas equation.

where,
P = final pressure in the flask = ?
R = gas constant = 0.0821 L.atm/mol.K
T = temperature = 
V = volume = 4.0 L
= moles of
= 0.20 mol
= moles of
= 0.20 mol
Now put all the given values in the above expression, we get:


Thus, the pressure in the flask after reaction complete is, 2.4 atm
A base and an Acid always react to form a salt and water
So, HCl + NaOH —> NaCl + HOH