(1) volume is given by
Volume=length*width*height=10cm*5cm*3cm=150 cm^3
(2) Density = mass/volume = 180 g / 150 cm^3 = (180/150) g / cm^3 = 1.2 g / cm^3
(3) Mass is independent of gravity, so the solid will have the same mass on the moon, on mars or any other planet.
Weight is the product of mass and acceleration due to gravity. Acceleration due to gravity on earth is 9.8 m/s^2, while on the moon, it is 1.62 m/s^2. Therefore the solid has a different weight on the moon than that on earth.
(4) If an object sinks in (pure) water, the density must be greater than one, since (pure) water has a density of exactly.1.0.
(5) Not all solid with he same dimensions have the same density, which depends on the nature of the material. Wood is lighter than water, while iron has a density of 7.8, gold has a density of 19.3, etc. However, all objects having the same dimensions have the same VOLUME.
(6) SI (Système International) is a unit based on metre, kilogram and second for length, mass and time measurements.
(7) Remaining definitions can be looked up in your textbook. If you need further definitions, please post.