The number of circles that touch all the straight lines $x+y=4$,$x-y=-2$,and $y=2$ is

If $A = \begin{bmatrix} 1 & 0 & 1 \\ 2 & 1 & 0 \\ 3 & 2 & 1 \end{bmatrix}$,then $\det(A)$ is equal to

Which of the following is the correct order of size of the given species?

In an experiment with a beam balance,an unknown mass $m$ is balanced by two known masses of $16\,kg$ and $4\,kg$ as shown in the figure. The value of the unknown mass $m$ is ......... $kg$.

Principal,azimuthal and magnetic quantum numbers are respectively related to

There are three lumps of a given radioactive substance. Their activity is in the ratio of $1 : 2 : 3$ now. What will be the ratio of their activities at any further date?