Question

choose a substance you're familiar with. what are its physical and chemical properties? How would you measure its density? What are some physical and chemical changes it can undergo?

Answer 1

You can look at magnesium, it can react with oxygen to form oxides. (chemical) it is malleable and a solid at room temperature. (physical)

to measure its density, the mass and volume can be worked out and from this density too. look up the equation, it is quite easy :) 

physical changes -- it can be melted, and oxidized <span />

Answer 2

Answer:

Let the substance is $H_2O$

1. Physical property is defined as the property of a substance which becomes evident during physical changes. Example: Melting point  of water is $0^0C$

Chemical property is defined as the property of a substance which becomes evident during chemical changes. Example: Reaction of water with active metals such as sodium

2. Density is measured as the ratio of amount of mass per unit volume.

$density=\frac{mass}{volume}$

3.  A chemical change is defined as a change in which a change in chemical composition takes place. A new substance is formed in these reactions.

$2H_2O\rightarrow 2H_2+O_2$

A physical change is defined as a change in which there is alteration in shape, size etc. No new substance gets formed in these reactions.

Example: evaporation of water