Answer:
B sugar in water
Explanation:
because sugar dissolves in water while the others don't
Answer: 
Explanation:Bond energy of H-H is 436.4 kJ/mole
Bond energy of C-H is 414 kJ/mol
Bond energy of C=C is 620 kJ/mol
Bond energy of C≡C is 835 kJ/mol

= {1B.E(C≡C)+2B.E(C-H) +1B.E(H-H)} - {1B.E(C=C)+4B.E(C-H)}


Answer:
Pb is the substance that experiments the greatest temperature change.
Explanation:
The specific heat capacity refers to the amount of heat energy required to raise in 1 degree the temperature of 1 gram of substance. The highest the heat capacity, the more energy it would be required. These variables are related through the equation:
Q = c . m . ΔT
where,
Q is the amount of heat energy provided (J)
c is the specific heat capacity (J/g.°C)
m is the mass of the substance
ΔT is the change in temperature
Since the question is about the change in temperature, we can rearrange the equation like this:

All the substances in the options have the same mass (m=10.0g) and absorb the same amount of heat (Q=100.0J), so the change in temperature depends only on the specific heat capacity. We can see in the last equation that they are inversely proportional; the lower c, the greater ΔT. Since we are looking for the greatest temperature change, It must be the one with the lowest c, namely, Pb with c = 0.128 J/g°C. This makes sense because Pb is a metal and therefore a good conductor of heat.
Its change in temperature is:

Answer:
The products react to reform the original reactants
E.g. Haber process of ammonia production