Answer:
The missing reactant is 
55/25Mn
Explanation:
asumming the missing reagent is A/Z X
In nuclear reaction , the sum of atomic number and mass number of on both sides musst be equal
Thus ,
Z + 54 = 79 + 0
Z = 25
The element with atomic number 25 is Mn
A + 143 = 197 +1
A = 55
Therefore, the missing reagent is 55/25Mn
Nuetrons+protons. and number 7 is electrons and protons
Marine food chains at risk of collapse, extensive study of world's oceans finds. ... The acidification of the ocean, where the pH of water drops as it absorbs carbon dioxide, will make it hard for creatures such as coral, oysters and mussels to form the shells and structures that sustain them.
The answer is the option (3) The geometric shape of a CH4 molecule
distributes the charges geometrically. the CH4 is a tetrahedral with the
Carbon atom in the center and the four H atoms in the vertices of the
tetrahedral. The C-H bond angles are all identical which makes the
molecule perfectly symmetrical and so any dipolar moment will cancel
making the molecule non polar.
