O2 is an example of a molecule
Because things that are burnt have been changed into something else like moldy bread thats cooked.
It is chemical change because you cannot unburn something.
Answer:
Strontium
Explanation:
The atomic number of strontium is 38.
It has 38 electrons.
It is alkaline earth metal. It has two valance electrons.
Strontium loses its two electrons and form cation with +2 charge.
Electronic configuration;
Sr₃₈ = [Kr] 5s²
The valance electrons present in 5s are lost by strontium atom and form Sr⁺² cation.
it is yellowish-white metal.
It is highly reactive.
It form salt with halogens.e.g
Sr + Br₂ → SrBr₂
IT react with oxygen and form oxide.
2Sr + O₂ → 2SrO
this oxide form hydroxide when react with water,
SrO + H₂O → Sr(OH)₂
With nitrogen it produced nitride,
3Sr + N₂ → Sr₃N₂
With acid like HCl,
Sr + 2HCl → SrCl₂ + H₂
<span>6mole of H2O contains 18×6 g=108 g</span>
<span>That the mass is far lesser
and distributed mistakenly, as compared to what the orbits of stars declare it
should be. Stars orbit more rapidly than the mass would predict, particularly
out toward the galactic edge. This means that there is more mass than has been
measured, and that it is spread out in a huge cloud around the galaxy. This is
one of the reasons why scientists believe that dark matter exists.</span>
