A molecule is defined as two or more atoms of the same element different element that are bound together. A molecule may be homonuclear, which means, it consists of atoms of one chemical element, as with oxygen (O2); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (H2O).
Answer:C3H8 +5O2-- >3CO2+4H2O, 330L of air,Hof C3H8= 2323.7 KJ/mol,dT=75.30
Explanation:
First We need to find a balanced equation to depict the combustion of the propane:
C3H8 +5O2-- >3CO2+4H2O
b)

330L of air
25 g C3H8 are equal to 44g and 5 mol of O2 will react with a mol of C3H8, each mol of O2 weigh 32g and for each L of air contains 0.275g of O2
c) 
the enthalpy of formation of propane will be the negative of the sum of the enthalpy of formation multiplied by the mols of the H2O and CO2
Hof C3H8= 2323.7 KJ/mol
d) We know that each 44g of C3H8(1mol) transfer 2219.2 KJ then:
= 1260.9KJ
We use the equation of heat transfered
Q=mCpdT
1260.9KJ= 4KJ *4.186KJ/Kg*°C *dT
We clear the equation
Q/mCp=dT
dT=75.30
Answer:
D
Explanation:
A synthesis reaction is a reaction in which two or more reactants combine to form a given product.
If we look closely at option D, you will notice that sulphur and oxygen combined together to form sulphur dioxide. That is a typical example of chemical synthesis.
Hence;
S + O2 ----->SO2 is a synthesis reaction.
A combination reaction<span> is a </span>reaction<span> in which two reactants combine to form one product. It is also called a synthesis reaction. A characteristic to this type of reaction would be that there would always be only one product. Hope this answers the question. Have a nice day. </span>
Answer : The correct option is, pressure.
Explanation :
The ideal gas equation is,

where,
P = pressure of the gas
V = volume of the gas
n = number of moles of gas
T = temperature of the gas
R = gas constant
The value of 'R' has several different values which are :




That means, the value of 'R' is different due the change in the pressure value and all the variables (temperature, volume and moles) are constant.
Hence, the correct option is, pressure.