Which of the following compounds has a positive enthalpy of solution?

Beryllium is placed above magnesium in the second group. Beryllium dust,therefore,when added to $MgCl_2$ solution will:

Ions of an element of group $1$ participate in the transmission of nerve signals and transport of sugars and amino acids into cells. This element imparts yellow colour to the flame in flame test and forms an oxide and a peroxide with oxygen. Identify the element and write chemical reaction to show the formation of its peroxide. Why does the element impart colour to the flame?

$A$ mixture of lime paste is composed of sand,water,and which of the following?

The correct order of electropositive nature of $Li$,$Na$ and $K$ is

Which one of the following reacts with concentrated sulphuric acid?