Ion having highest hydration enthalpy among the given alkaline earth metal ions is:
A block of certain mass is placed on a rough floor. The coefficients of static and kinetic friction between the block and the floor are 0.4 and 0.25 respectively. A constant horizontal force \( F = 20 \, \text{N} \) acts on it so that the velocity of the block varies with time according to the following graph. The mass of the block is nearly (Take \( g = 10 \, \text{m/s}^2 \)): 
Group one of alkali metals is s-block elements with just one electron in their s-orbital. They are are alkali metals. They are named so because of the alkaline nature of the hydroxides and oxides.
Alkali metals are characterized by one s-electron in the valence shell of their atoms.
Alkali metals have a corresponding [Noble gas] ns1 electronic configuration. They occupy the first column of the periodic table. Alkali elements are:
They have occupied successive periods from first to seven. Francium is a radioactive element with very low half-life.
This makes them the most electropositive elements and due to the same reason, they are not found in the pure state.