Q1.The table below shows data for the four hydrocarbons ethyne, propyne, propene and propane. AHc is the standard enthalpy of combustion of these hydrocarbons.
Compound
Name
M
-AHC
/kJ mol
HCECH
ethyne
26
1300
HC-CCH,
propyne
40
1940
H. C=CHCH,
propene
42
2060
CH, CH, CH
propane
44
2220
The complete combustion of 2.0 g of one of the above hydrocarbons releases exactly 100 kJ of
heat energy
This hydrocarbon is
A
ethyne
B
propyne
C
propene
D
propane
(Total 1 mark)

Explanation:

It often helps to write the heat as if it were a reactant or a product in the thermochemical equation.

Then you can consider it to be "moles" of "kJ"  

We will need a chemical equation with masses and molar masses, so, let's gather all the information in one place.

M_r:               26

              2H-C≡C-H + … ⟶   1300 kJ + …

m/g:              2.0

1. Moles of HC≡CH

2. Heat released

The molar ratio is 1300 kJ:1 mol HC≡CH

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.