The number of valence electrons in a graphite atom is:

In a sample of ethyl ethanoate (CH₃COOC₂H₂), the two oxygen atoms have the same number of electrons but different number of neutrons. Which of the following is the correct reason for it?

Which of the following elements does not exhibit electrovalency?

The atomic numbers of four elements A, B, C and D are 12, 13, 15 and 3 respectively. The element which cannot form a cation is:

The number of valence electrons in a sulphide ion, S^2-, is: