Lithium nitrate and sodium nitrate,when heated separately,respectively,give

Equimolar solutions of the following compounds are prepared separately in water. Which will have the lowest $pH$ value?

Which of the following metal ions plays an important role in muscle contraction?

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The alkali metals and their salts impart characteristic colour to reducing flame.
Reason $R$: Alkali metals can be detected using flame tests.
In the light of the above statements,choose the most appropriate answer from the options given below.

An element $A$ of group $1$ shows similarity to an element $B$ belonging to group $2$. If $A$ has maximum hydration enthalpy in group $1$,then $B$ is:

The element with atomic number $55$ belongs to