What is the S.I unit of relative density and density?

Why does relative density has no units ?

 why does an iron needle sink in water, but not an iron ship? anyone know the answer.

 why does an iron nail sink but an iron ship float?

Explain the statement 'relative density of brass is 8.4.'

1-Find the massof an ice cubeof edge 2cm. The densityof ice =900kg/m³

2-A beaker weighs 120g when empty and 280g when filled with kerosene. Find the volume of the beaker. The density of kerosene=800kg/m³

3-A metal ball weighs 1.8kg. The volume of the ball is 250cc. Find the density of the metal.

4-The capacity of an RD bottle is 50cc and its mass is24.5g when empty. Find its mass when it is filled with a liquid of density 800kg/m³

5-The mass of an empty RD bottle is 24.5g. Its mass is 74.4g when filled with water and 87g when filled with a liquid. Find the relative density of the liquid.

PLEASE ANS. IT QUICKLY WITH DETAILS MY EXAMS ARE APPROACHING

 An empty density bottle weighs 22g. When completely filled with water, it weighs 50g. When completely filled with brine solution it weighs 54 g. Calculate 

a) volume of density

b) density of brine solution

(Please help me to solve it in detail) 

wat is the difference between mass and weight?

THE DENSITY OF MERCURY IS 13.6G/CM3. WHAT DOES THIS STATEMENT IMPLY???

What is difference between density and relative density ?

What is SI system of unit? Name two other systems of units?

does sponge float in water?

why do we use a physical balance and not a beam balance in al ab

1.  find the mass of an ice cube edge 2cm.the density of ice=900kg/m3.?
2.  

 how are convection currents set up in the air ???