Well first we can say that B. and D. are out BC they are physical changes we are looking for chemical changes when burning gas, the gas is burning and converting into heat energy AKA FIRE!!!. so the answer is indeed (A. <span>Chemical bonds are broken and others are formed.)
</span>
<span />BTW im not a girl every one ask that. the girls in the pic is my GF
any ways i hope you can learn something new from this. :) <3 have any amazing day
C9H20 + 14O2 --> 9CO2 + 10H2O
D. Being cold temperatures can result in a cold nose. With prolonged exposure The body will start to lose heat faster than it can generate it, this is the result of hypothermia.
The % yield of Ca(OH)₂ : 62.98%
<h3>Further eplanation
</h3>
Percent yield is the compare of the amount of product obtained from a reaction with the amount you calculated
General formula:
Percent yield = (Actual yield / theoretical yield )x 100%
An actual yield is the amount of product actually produced by the reaction. A theoretical yield is the amount of product that you calculate from the reaction equation according to the product and reactant coefficients
Reaction
CaO + H₂O ⇒ Ca(OH)₂
mass CaO= 4.2 g
mol CaO(MW=56,0774 g/mol) :
mol Ca(OH)₂ based on mol CaO
mol ratio CaO : Ca(OH)₂,= 1 : 1, so mol Ca(OH)₂ = 0.075
mass Ca(OH)₂(MW=74,093 g/mol) ⇒ theoretical
% yield :