Answer:
Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. Thomson's plum pudding model of the atom had negatively-charged electrons embedded within a positively-charged "soup.
The correct answer is option 1. The mass of the products is less than the mass of the reactants because some of the mass has been converted to energy. Fusion reaction happens when two or more nuclei combine or collide to form an element with a higher atomic number. In this process, some of the matter of the fusing nuclei is converted to energy.
Answer : The balanced chemical equation is,

Explanation :
Balanced chemical equation : It is defined as the number of atoms of individual elements present on the reactant side must be equal to the number of atoms of individual elements present on product side.
The given unbalanced chemical reaction is,

This chemical reaction is an unbalanced reaction because in this reaction, the number of atoms of individual elements are not balanced.
In order to balanced the chemical reaction, the coefficient 2 is put before the
, the coefficient 3 is put before the
and the coefficient 4 is put before the
.
The energy evolved in this reaction = 
Thus, the balanced chemical reaction will be,

Answer:
Calcium carbonate reacts with hydrochloric acid to form carbon dioxide gas. 2HCl (aq) + CaCO 3(s) CaCl 2 (aq) + CO 2(g) + H 2 O (l).