The number following the name of the element is the number of subatomic particles inside the nucleus of the atom. This means that it is the mass number of the isotope. The average atomic mass of the element is the sum of the products of the percentage abundance and mass number of the naturally occurring isotopes.
Since, the average atomic mass of the hydrogen is nearest to 1 then, the most abundant isotope should be hydrogen-1.
Hthe heat required to change the temperfature of 100 grams of water from 25 to 55 c is calculated as below
Q(heat) = M(mass) x C(specific heat capacity) x delta T(change in temperature)
M= 100 grams
C= 4.18 j/g/c
delta T= 55-25 =30c
Q=100 g x4.814 j/g/c x 30c = 12552 joules
