Which of the following pairs is correctly matched?

If the lines $\frac{x-1}{2}=\frac{y+1}{3}=\frac{z-1}{4}$ and $\frac{x-3}{1}=\frac{y-k}{2}=\frac{z}{1}$ intersect,then the value of $k$ is:

Which of the following is the only taxonomic category that has a real existence?

The surface of a metal is illuminated with light of $400\, nm$. The maximum kinetic energy of the ejected photoelectrons was found to be $1.68\, eV$. The work function of the metal is.......$eV$ $(hc = 1240\, eV\, nm)$.

If $a, b, c$ are three non-coplanar vectors,then the vector equation $r = (1 - p - q)a + pb + qc$ represents a

Which of the following pairs represents linkage isomerism?