In the process of attempting to characterize a substance, a chemist makes the following observations. which are physical properties and which are chemical properties?
(a) the substance is a silvery white, lustrous metal
(b) it melts at 649°c and boils at 1105°c
(c) its density at 20°c is 1.738 g/cm3
(d) the substance burns in air, producing an intense

a) The substance is a silvery white, lustrous metal :physical property.  

b) It melts at 649°C and boils at 1105°C : physical property.  

c) Its density at 20°C is : physical property.  

d)  The substance burns in air, producing an intense white light : chemical property

Explanation:

Chemical property is defined as the property of a substance which is observed during a reaction where the chemical composition identity of the substance gets changed.

Physical property is defined as the property which can be measured and whose value describes the state of physical system. For Example: State, density etc.

a) The substance is a silvery white, lustrous metal is a physical property

b) It melts at 649°C and boils at 1105°C is a physical property.  

c) Its density at 20°C is is a physical property.  

d) The substance burns in air, producing an intense white light is a chemical property

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.

it's filtration, but this is an assumption so my apologies if i got this