Isotope, Formation of Ion, Valency

The ratio of non-metal atoms to the number of atoms of two non-metallic oxides A and B are $0.33$ and $0.25$, respectively. Find the valencies of non-metals present in those non-metallic oxides.

${}_8{}^{16}\mathrm{O}$ and ${}_8{}^{18}\mathrm{O}$ are isotopes while ${}_{20}{}^{40}\mathrm{Ca}$ and ${}_{18}{}^{40}\mathrm{Ar}$ are isobars.

What is mean by valency?

Which of these statements is true for ions? Circle ‘Yes’ or ‘No’ for the correct response.

What are cations?

What is carbonate?

Can all elements form both electro valency and covalency?

The half-life of a radioisotope is $4$ hours. If the initial mass of the isotope was $200 \mathrm{g}$, the mass remaining after $24$ hours undecayed

Which one of the following is cation 

Valence electron in ${\mathrm{Cl}}^{-}$ ions is 

Isotopes of an element contains 

The following is the correct decreasing order of the ionic radii- 

The number of protons in one atom of an element $\mathrm{X}$ is $8$. What will be the number of electrons in its ion ${\mathrm{X}}^{-2}$?

Hydrogen contains three types of atoms (${}_1{}^1\mathrm{H}$ protium, ${}_1{}^2\mathrm{H}$ deuterium, ${}_1{}^3\mathrm{H}$ tritium). These atoms are

What is meant by valency? Explain in detail.

Which represents the electron arrangement of Fluoride ion? 

Since there are 24 electrons and 29 neutrons in X²⁺ ion, which of the following is an isotope of this ion?

In a sample of ethyl ethanoate (CH₃COOC₂H₅), the two oxygen atoms have the same number of electrons but different number of neutrons. Which of the following is the correct reason for this?

The number of valence electrons in Cl^- ion is 

Potassium and potassium ions: