How many $EDTA$ molecules are required to make an octahedral complex with a $Ca^{2+}$ ion?

In the circuit shown in the figure below, which of the following statements is incorrect?

Assertion $(A)$ The effective resistance of the network between $P$ and $Q$ is $\frac{4}{5} r.$

Reason $(R):$ Symmetry can be applied to be network with respect to centre.

Assertion $A$: Barium is not required in the normal biological processes of the human body.
Reason $R$: Barium does not exhibit more than one oxidation state.

Two bar magnets $A$ and $B$ are placed one over the other and are allowed to vibrate in a vibration magnetometer. They make $20$ oscillations per minute when the similar poles of $A$ and $B$ are on the same side,while they make $15$ oscillations per minute when their opposite poles lie on the same side. If $M_A$ and $M_B$ are the magnetic moments of $A$ and $B$ and if $M_A > M_B$,the ratio of $M_A$ and $M_B$ is

Which of the following is not true for glucose?