The mass of hydrogen is 1.6726 x 10–27 kg, and the mass of helium is 6.6465 x 10–27 kg. Given this, which of the following nuclear reactions would result in a decrease of total mass, and thus a release of energy, while keeping the same number of particles involved?

A. A helium nucleus breaks up into four hydrogen nuclei.
B. Four hydrogen nuclei combine into one helium nucleus
C. Two hydrogen nuclei combine into one helium nucleus.
D. A helium nucleus breaks up into two hydrogen nuclei

B.Four hydrogen nuclei combine into one helium nucleus.

Explanation:

Mass energy which is stored in a matter itself can be very powerful. A small amount of mass can result in a very large amount of energy as the speed of light is very large.

If we consider the two elements hydrogen and helium, a hydrogen nucleus is made of one proton  and a helium nucleus is made of two protons and two neutrons.

The mass of hydrogen is 1.6726 x 10–27 kg, and the mass of helium is 6.6465 x 10–27 kg.

Four hydrogen nuclei combine into one helium nucleus would lead to decrease of total mass, and thus a release of energy such that the number of particles involved remains same.

rosa was looking for patterns to predict the products of chemical reactions. she recorded three similar decomposition reactions in the table.she should record 2licl + 3o2.

in the last row of the table. it is the thermal decomposition of chlorate lithium, hence, she should record these products as: lithium chloride ( 2licl ) and oxygen ( 3o2 )   2 > 2 licl + 3o2.