Question

If two gases are present in a container, the total pressure in the container is equal to
the sum of the pressures that are exerted by each of the two gases.
twice the sum of the pressures that are exerted by the individual gases.
the sum of the pressures that each gas would exert if they occupied twice the volume.
the sum of the pressures that each gas would exert if they occupied half the volume.

Answer 1

the sum of the pressures that are exerted by each of the two gases.

( Dalton's law of partial pressures: P_total = P1 + P2. For ideal gases P_i = n_iRT/V, so P_total = (n1+n2)RT/V = P1+P2.)