The resolving limit of a healthy human eye is about

Which of the following radioactive isotopes is used in the detection of thyroid cancer?

In the ground state,an element has $13$ electrons in the $M$ shell. The element is

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

Let $a, b$ and $c$ be distinct and none of them is equal to $1$. If the lines $x+ay+a=0$,$bx+y+b=0$ and $cx+cy+1=0$ are concurrent,then the value of $\frac{a}{a-1}+\frac{b}{b-1}+\frac{c}{c-1}$ is

An infinitely long straight conductor is bent into the shape as shown below. It carries a current of $I$ ampere and the radius of the circular loop is $R$ metre. Then,the magnitude of magnetic induction at the centre of the circular loop is