The volume of a sample of hydrogen gas was decreased from 12.85 l to 6.14 l at constant temperature. if the final pressure exerted by the hydrogen gas sample was 7.40 atm, what pressure did the hydrogen gas exert before its volume was decreased?

3.79 atm Explanation: Assuming ideal behavior, the gas sample should satisfy the Boyle's law, which states that P ⋅ V = a constant when temperature is held constant. [1] In other words, the pressure the gas exerts is inversely related to the volume of the airtight container. Therefore P 1 ⋅ V 1 = P 2 ⋅ V 2 P 1 = P 2 ⋅ V 2 V 1 = P 2 ⋅ V 2 V 1 Evaluate with V 1 = 13.16 L , V 2 = 6.45 L , P 2 = 7.73 atm as given in the question: P 1 = 7.73 atm ⋅ 6.45 L 13.16 L = 3.79 atm (rounded to three significant figures)

your answer would be a. 12.5 kg

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.