Elements A, B and C have atomic numbers 9, 20 and 10 respectively.
Write down the formula of the compound formed by two of the above elements.

Elements X, Y and Z have atomic numbers 6, 9 and 12 respectively. Which one : forms an anion

Elements X, Y and Z have atomic numbers 6, 9 and 12 respectively. Which one : forms a cation

(a) List two limitations of Newlands' Law of Octaves. (b) Write the electronic configuration of two elements A and B whose atomic numbers are 20 and 17 respectively. Write the molecular formula of the compound formed when element A reacts with element B. State whether this compound is acidic, basic or neutral. Give reason to justify your answer.

There are three elements E, F, G with atomic numbers 19, 8 and 17 respectively. Give the molecular formula of the compound formed between E and G and state the type of chemical bond in this compound.

Elements X,Y and Z have 4,5 and 7 valence electrons respectively, (i) Write the molecular formula of the compounds formed by these elements individually with hydrogen (ii) which of these compounds will have the highest dipole moment ?

Elements X,Y and Z have 4,5 and 7 valence electrons respectively, (i) Write the molecular formula of the compounds formed by these elements individually with hydrogen (ii) which of these compounds will have the highest dipolw moment ?

Elements A, B and C have atomic numbers 9, 20 and 10 respectively. State which one is : (i) a non-metal (ii) a metal (iii) chemically inert.

Five atoms are labelled from A to E Write down the formula of the compound formed between C and D.

The elements A, B, C, D and E have atomic number 9, 11, 17, 12 and 13 respectively. Which pair of elements belongs to the same group ?

Three elements 'X', 'Y' and 'Z' have atomic numbers 18, 19 and 20 respectively. How many electrons are present in the M shell of these elements?