The main formula is as follow is explained in the attached file (please look at the examples)
the 1,3- butadiene is h2c=ch-ch=ch2, so we have
sp² sp² sp² sp²
h2c = ch - ch = ch2
<span>the hybridization of the carbon atoms is </span>sp² : trigonal planar
The given mass of cobalt chloride hydrate = 2.055 g
A sample of cobalt chloride hydrate was heated to drive off waters of hydration and the anhydrate was weighed.
The mass of anhydrous cobalt chloride = 1.121 g anhydrate.
The mass of water lost during heating = 2.055 g - 1.121 g = 0.934 g
Converting mass of water of hydration present in the hydrate to moles using molar mass:
Mass of water = 0.934 g
Molar mass of water = 18.0 g/mol
Moles of water = 
Mercury is the only metal that is a liquid at room temperature.
your answer is A.
It is used in thermometer.
It’s the third one because Cl has 17 protons bc of the numeric number and 18 electrons bc it’s always the opposite and 18 neutrons because you subtract 35-17=18