According to the brønsted-lowry definition, in which of the following reactions does water act as an acid?
a) hc2h3o2(aq) + h2o(l) → h3o+(aq) + c2h3o2-(aq)
b) h2o(l) + no2-(aq) → hno2(aq) + oh-(aq)
c)hcl + h2o(l) → h3o+(aq) + cl-(aq)
d)h2o(l) + nh4+(aq) → h3o+(aq) + nh3(aq)

b..

is the correct one

explanation:

covalent bonds form as valence electrons are shared between two atoms. lewis structures and structural formulas are common ways of showing the covalent bonding in organic molecules. formal charge describes the changes in the number of valence electrons as an atom becomes bonded into a molecule.

the product of the pressure and volume is also constant

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer