Chemical changes only happen when the object changes form. Color is a physical property because you're not changing the object that you have, compressibility is also a physical property because you still have the same substance before and sfter, malleability again is another physical. Heat of combustion is physical, when you burn things it changes the substance. :)
Answer: <u>Four</u>Explanation: Calcium Sulfide is an ionic compound made up of Ca²⁺ and S²⁻.
Ca²⁺ is formed as,
Ca → Ca²⁺ + 2 e⁻
These two electrons are accepte by Sulfur as,
S + 2 e⁻ → S²⁻
So, before accepting 2 electrons S was having six valence electrons, after accepting two electrons from Ca it has 8 electrons which are present in four pairs as shown below,
Aqueous solutions of barium nitrate and potassium phosphate are mixed.
What is the precipitate and how many molecules are formed?
Barium nitrate has a chemical symbol of Ba(NO3)2 and potassium phosphate
has a chemical symbol K2PO4. The reaction between these two is a double
replacement reaction yielding barium phosphate and potassium nitrate.
The chemical equation representing the reaction is,
Ba(NO3)2 + K2PO4 à KNO3 +
BaPO4