The unit of time is:

1. light year
2. parsec
3. leap year
4. angstrom

1 Å is equal to:

1. 0.1 nm
2. 10^-10cm
3. 10^-8m
4. 10⁴µ

One solar mass is equal to :

1. 3 x 10²⁰ kg
2. 2 x 10²⁷ kg
3. 2 x 10³⁰ kg
4. 3 x 10³⁰ kg

One lunar cycle is nearly equal to:

1. 28.5 days
2. 29.5 days
3. 30 days
4. 30.5 days