the compound is B.
Water is a compound because it is made up of water molecules.
Answer:
platinum-189 symbol is PT
<u>Answer: </u>
A sample initially contained 150 mg of radon-222. After 11.4 days only 18.75mg of the radon-222 in the sample remained where 3 half-lives have passed
<u>Explanation:</u>
Given, the initial value of the sample,
= 150mg
Final value of the sample or the quantity left, A = 18.75mg
Time = 11.4 days
The amount left after first half life will be ½.
The number of half-life is calculated by the formula

where N is the no. of half life
Substituting the values,


On equating, we get, N = 3
Therefore, 3 half-lives have passed.
To test for hydrogen, burn a candle near the suspected source of hydrogen. If you hear a squeaky pop sound, hydrogen is present because when hydrogen gas burns, it makes a squeaky pop sound.
Aluminum can be oxidized by
and 
<h3>What is oxidizing?</h3>
Some of the metal corrodes (or oxidizes) and forms the corresponding metal oxide on the surface as a result of a chemical reaction between the metal surface and the oxygen in the air. The corrosion products that occur in some metals, like steel, are highly apparent and loose.
According to reactivity series (The array of metals in the descending order of their reactivities is referred to as the metals' reactivity series. It is sometimes referred to as the metals in the activity series.)
Lithium and calcium ions are more reactive than aluminum ion and they are less electronegative.
Since silver and tin are more electronegative than aluminum so, they cannot oxidize aluminum.
∴
and
ions can oxidize aluminum.
Learn more about electronegativity here brainly.com/question/16446391
#SPJ10