Acid-base indicator changes color based on pH.
drop some in a solution n watch the color changes. different indicators show different colors at different pH. they usually have standard colors for comparison.
Answer:
silicon tetrachloride or tetrachlorosilane
Answer:

Explanation:
We are given the percent composition: 22.5% phosphorus and 77.5% chlorine.
We can assume there are 100 grams of this compound. We choose 100 because we can simply use the percentages as the masses.
Next, convert these masses to moles, using the molar masses found on the Periodic Table.
- P: 30.974 g/mol
- Cl: 35.45 g/mol
Use the molar masses as ratios and multiply by the number of grams. 

Divide both of the moles by the smallest number of moles to find the mole ratio.


The mole ratio is about 1 P: 3 Cl, so the empirical formula is written as:<u> PCl₃</u>
Answer:
oxidation number
Explanation:
Describes the degree of oxidation of an atom in a chemical compound.
Answer:
Two (2) electron pairs
Explanation:
The sharing of electron pairs by atoms forms a type of bond called COVALENT bond. Atoms that form covalent bonding (share electrons) do so in order to fill their outermost electron shells, hence, gain chemical stability.
However, when two atoms like carbon share TWO PAIRS of electrons with each other, a DOUBLE BOND is formed. An example is the double bond formed in Ethylene (2HC=CH2). A total of four valence electrons (a pair from each carbon) are shared between the two carbon atoms.