If a polygon of $n$ sides has $275$ diagonals,then $n$ is equal to

The silicate having one monovalent corner oxygen atom in each tetrahedron unit is:

Which of the following oxides is strongly basic?

If $g$ is the acceleration due to gravity on the earth's surface,the gain in the potential energy of an object of mass $m$ raised from the surface of the earth to a height equal to the radius $R$ of the earth is

In polymeric $(BeCl_2)_n$,there are