For idea gases, volume is directly proportional to temperature. That is, an increase in temperature leads to increase in volume and vice versa.
Therefore,
V1/T1 = V2/T2 => T2 = (V2*T1)/V1
Assuming that the balloon is spherical in shape,
V= 4/3*pi*R^3.... In the formula for calculating T2, 4/3*pi cancels out.
R1 = 30/2 15 cm; R2 = 30.5/2 = 15.25 cm; T1 = 20+273.15 =293.15 K
Therefore,
T2 = (R2^3*T1)/R1^3 = (15.25^3*293.15)/15^3 = 308.05 K = 34.9 °C
Time period of any moon of Jupiter is given by

from above formula we can say that mass of Jupiter is given by

now for part a)

T = 1.77 day = 152928 seconds
now by above formula



Part B)

T = 3.55 day = 306720 seconds
now by above formula



Part c)

T = 7.16 day = 618624 seconds
now by above formula



PART D)

T = 16.7 day = 1442880 seconds
now by above formula



heya mate
the planet Jupiter has most gravity due to its size
I think you can google this because I really don’t know the answer I’m so sorry