The statement is false because endothermic reactions have a positive enthalpy change, because heat is being added to the system because it requires more energy to react
<u>Answer:</u> The percent composition of hydrogen in the sample is 15.22 %
<u>Explanation:</u>
We are given:
Mass of hydrogen = 7 grams
Mass of nitrogen = 32 grams
Mass of carbon = 7 grams
Total mass of the sample = 7 + 32 + 7 = 46 grams
To calculate the percentage composition of hydrogen in sample, we use the equation:

Mass of sample = 46 g
Mass of hydrogen = 7 g
Putting values in above equation, we get:

Hence, the percent composition of hydrogen in the sample is 15.22 %
B) They have protons that are identical to the protons of all other elements
Answer:
Four (4) hydrogen atoms
Explanation:
C=C-C(triple bond)C
only four hydrogen atoms can bond with the vacant space
Answer:
277.7 g of CO2
Explanation:
Equation of reaction
C13H18O2 + 11O2 ---> 13CO2 + 9H2O
From the equation of reaction
1 mole of ibuprofen produces 13 moles of CO2
Molar mass of ibuprofen is 206g
Molar mass of CO2 is 44g
13 moles of CO2 weighs 572g
Therefore, 100g of ibuprofen will produce (100×572)/206 of CO2
= 277.7g