Which of the following can be added to remove the permanent hardness of water?

Which of the following is a wheat fruit?

$Ge$ and $Si$ diodes conduct at $0.3\,V$ and $0.7\,V$ respectively. In the following figure,if the $Ge$ diode connection is reversed,the value of $V_0$ changes by.....$V$.

Cyclic hydrocarbon molecule $A$ has all the carbon and hydrogen atoms in a single plane. All the carbon-carbon bonds are of the same length,which is less than $1.54 \ \mathring{A}$ but more than $1.34 \ \mathring{A}$. The $C-C$ bond angle will be

The time constant of an inductance coil is $3 \text{ ms}$. When a $90 \Omega$ resistance is joined in series,the time constant becomes $0.5 \text{ ms}$. The inductance and the resistance of the coil are:

The product of the lengths of perpendiculars drawn from any point on the hyperbola $x^2 - 2y^2 - 2 = 0$ to its asymptotes is: