Calculate the work function that requires a 475 nm photon to eject an electron of 1.25 ev.

The work function has the formula
E = h v

where
E is the energy
h is the constant
v is the frequency

Since the given is wavelength, we use the relationship between frequency and wavelength
v = c / λ
where
c is the speed of light
λ is the wavelength

So.
E = h c / λ
h = Eλ / c = 1.25 eV (475x10-9m) / (3x10^8 m/s)
h = 1.9792 x 10^-15

The work function is:
E = 1.9792 x 10-15 v

2.94kg

Explanation: Using Kepler's law of planetary motion which states that, the square of the orbital period of a planet is proportional to the cube of the semi major axis of it's orbit.

Sirius is the name given to the brightest star in the sky

It could be literally interpreted as;

1/mass of planet = (orbital period in years^2 ÷ semi major axis in AU^3)

Orbital period = 7months is equivalent to 7/12 = 0.5833 years

Semi major axis = 1AU

Therefore, mass of Sirius is given by:

1/Mass = (orbital period^2 ÷ semi major axis^3)

1/Mass = (0.5833^2 ÷ 1^3)

1/Mass = 0.3402 ÷ 1

1/Mass = 0.3402

Therefore,

Mass = 1/0.3402 = 2.94kg