The metal iridium has an FCC crystal structure. If the angle of diffraction for
the {220} family of parallel planes occurs at 69.22? (first-order reflection) when
monochromatic x-radiation having a wavelength of 0.1542 nm is used,
compute
(a) the interplanar spacing for this set of planes, and
(b) the atomic radius for an iridium atom

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance

it would be b. 6co2 + 6h2o --> c6h12o6 + 6o2