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

If $(h, k)$ is the image of the point $(2, -3)$ with respect to the line $5x - 3y = 2$,then $h + k$ is equal to

Ammonia with excess of $Cl_2$ forms:

The basis of the quantum mechanical model of an atom is

When a wire of length $10 \ m$ is subjected to a force of $100 \ N$ along its length,the lateral strain produced is $0.01 \times 10^{-3} \ m$. The Poisson's ratio was found to be $0.4$. If the area of cross-section of the wire is $0.025 \ m^2$,its Young's modulus is

The figure shows a rough sketch of a meter bridge. The galvanometer $(G)$ shows zero deflection at a length $\ell \, cm$. Now,$R_1$ and $R_2$ are interchanged,then the balancing length increases by $25 \, cm$. Find the ratio $R_1/R_2$.