The O2 produced from the decomposition of the 1.0 L sample of H2O2 is collected in a previously evacuated 10.0 L flask at 300. K

Explanation:

Initial moles of ethanoic acid = 0.020 mol

At equilibrium, half of the ethanoic acid molecules have reacted.

Thus, moles of ethanoic acid reacted = 0.020 mol * (50% / 100%)

                                                                     = 0.010 mol

Moles of ethanoic acid remaining = 0.020 mol - 0.010 mol = 0.010 mol

The moles of product gas formed are determined as follows:

0.010 mol CH3COOH * (1 mol / 2 mol CH3COOH)

= 0.005 mol

Consequently, the total moles of gas present in the vessel at equilibrium are 0.010 mol CH3COOH and 0.005 mol

Total gas moles at equilibrium = 0.010 mol + 0.005 mol = 0.015 mol

Next, let’s determine the pressure:

0.020 mol of gas has a pressure of 0.74 atm; so under the same conditions, we find the pressure exerted by 0.015 mol of gas:

P1/n1 = P2/n2

P2 = P1*(n2 / n1)

      = 0.74 atm * (0.015 mol / 0.020 mol)

     = 0.555 atm

Answer: The correct option is, 30 protons

Explanation:

Element = Zinc

Atomic number = 30

Atomic mass number = 65

Recall that the atomic number equals the number of electrons and protons.

Atomic number = Number of electrons = Number of protons = 30

Number of neutrons = Atomic mass - Number of protons = 65 - 30 = 35

Therefore, an uncharged zinc atom has 30 protons.