$A$ physical quantity that has a direction is called...

Two vectors $A$ and $B$ are inclined at an angle $\theta$. Their resultant $R$ makes an angle $\phi$ with vector $A$. If the directions of $A$ and $B$ are interchanged,the resultant will have the same:

Which of the following dopant is $NOT$ used in $Ge$ to obtain $n$-type semiconductor?

What is the uncertainty in the velocity of an electron if the uncertainty in the measurement of its position is $50 \text{ pm}$? $(m_e = 9.1 \times 10^{-31} \text{ kg}, h = 6.63 \times 10^{-34} \text{ Js}, \pi = 3.142)$

Two vectors of same magnitude act at a point. Twice the product of the magnitudes of two vectors is equal to the square of the magnitude of their resultant. The angle between the two vectors is (in $^{\circ}$)

A spherical raindrop evaporates at a rate proportional to its surface area. The differential equation involving the rate of change of its radius $r$ with time $t$ is ... (where $k$ is a positive constant)