An atom A has one electron in its outer shell and an atom B has six electrons in its outer shell. When they react, the most likely formula for the compound is

In the molten state, an ionic compound conducts electricity because

In dry ice (solid carbon dioxide) the carbon dioxide molecules are held together by

Polyethene can be produced in branched or unbranched form. Compared to the branched form, the unbranched form shows

The number of lone pairs of electrons in the nitrogen molecule is

Ionic compounds are often brittle, so that the crystal shatters when hit. This is because

Allotropes are

A doubly negatively charged ion has either protons. The number of electrons in the ion is

Which one of the following has a different electron configuration from the others?

Which one of the following pairs of elements is most likely to combine to from a compound with properties similar to those of sodium chloride?

Isotopes of an element contain:

The relative atomic mass of magnesium is 24.31. The most important reason why it is not a whole number is that

The boiling temperature of alkanes increases as the number of carbon atoms increases because

Which one of the following groups of substances shows only covalent compounds?

Metals are malleable and ductile because when a metal is hit