Name of first 30 elements with his valency and symbol

Explanation:

ElementAtomic NumberValency

Valency of Hydrogen11

Valency of Helium20

Valency of Lithium31

Valency of Beryllium42

Valency of Boron53

Valency of Carbon64

Valency of Nitrogen73

Valency of Oxygen82

Valency of Fluorine91

Valency of Neon100

Valency of Sodium (Na)111

Valency of Magnesium (Mg)122

Valency of Aluminium133

Valency of Silicon144

Valency of Phosphorus153

Valency of Sulphur162

Valency of Chlorine171

Valency of Argon180

Valency of Potassium (K)191

Valency of Calcium202

Valency of Scandium213

Valency of Titanium224

Valency of Vanadium235,4

Valency of Chromium242

Valency of Manganese257, 4, 2

Valency of Iron (Fe)262, 3

Valency of Cobalt273, 2

Valency of Nickel282

Valency of Copper (Cu)292, 1

Valency of Zinc302

answer: e.   sour taste

explanation: acids are those substances which dissociates in water to give ions. as they dissociate to give ions, they act as electrolytes and thus are electrically conductive. acids are sour in taste. example: hcl

bases are those substances which dissociates in water to give ions or accepts ions. as they dissociate to give ions, they act as electrolytes and thus are electrically conductive. bases are bitter in taste. bases are slippery in nature.

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.